*THE  ENGINEER"  SERIES 


WHAT  INDUSTRY  OWES 
TO  CHEMICAL  SCIENCE 


RICHARD  B.PILCHER 

AND 

FRANK  BUTLER-JONES 

WITH  AN  INTRODUCTION  BY 
SIR  GEORGE  BEILBY 


"  THE    ENGINEER "  SERIES. 

WHAT   INDUSTRY  OWES 
TO   CHEMICAL  SCIENCE. 


By 

RICHARD  B.  PILCHER, 

Registrar  and  Secretary  of  the  Institute  of 
Chemistry  of   Great    Britain  and   Ireland; 

AND 

FRANK  BUTLER-JONES,  B.A.  (Cantab.),  A.I.C., 

Assistant,  Laboratory  of  the    Department  of 
Explosives   Supplies,  Ministry  of  Munitions. 

With  an  Introduction  by 
Sir  GEORGE  BEILBY,  LL.D.,  F.R.S., 

Past  President  of  the  Inttitute  of  Chemistry 
and   of   the    Society    of   Cktmieal    Industry. 


New  York : 

D.  VAN  NOSTRAND  COMPANY, 
25,  Park  Place. 

1918. 


PRINTED  IN  GREAT  BRITAIN. 


CONTENTS. 


INTRODUCTION       vii 

PREFACE         xiii 

Chap.  I.  MINERALS  AND  METALS        1 

II.  HEAVY  CHEMICALS  AND  ALKALI 22 

III.  COAL  AND  COAL  GAS      34 

IV.  DYES,  EXPLOSIVES,  AND  CELLULOSE  ...  41 
V.  OILS,  FATS,  AND  WAXES       53 

VI.  LEATHER 59 

VII.  RUBBER 63 

VIII.  MORTAR  AND  CEMENT 65 

IX.  REFRACTORY  MATERIALS     68 

X.  GLASS  AND  ENAMELS    70 

XI.  POTTERY  AND  PORCELAIN    77 

XII.  CHEMICAL  PRODUCTS' 80 

XIII.  PHOTOGRAPHY        90 

XIV.  AGRICULTURE  AND  FOOD      95 

XV.  BREWING 104 

XVI.  ALCOHOL,  WINES  AND  SPIRITS     109 

XVII.  TOBACCO,  INKS,  PENCILS,  ETC.    ...     ...  115 

XVIII.  GASES      122 

XIX.  GOVERNMENT  CHEMISTRY     133 

CONCLUSION 138 

BIBLIOGRAPHY       141 

INDEX  144 


387485 


INTRODUCTION. 


AMIDST  the  flood  of  opinions  and  advice  on  the 
relations  of  science  to  education  and  industrial 
prosperity  with  which  we  have  been  deluged 
during  the  past  two  or  three  years,  we  may  turn 
with  welcome  relief  to  the  unembellished  records 
of  work  done  and  of  ends  accomplished  which  the 
authors  have  here  presented  for  our  enlightenment 
and  encouragement.  The  majority  among  us 
stood  much  in  need  of  enlightenment  on  this 
subject,  and  many  of  us  will  feel  grateful  for  the 
encouragement  which  is  to  he  derived  from  these 
records  of  past  achievement.  These  records  supply 
a  complete  answer  to  a  question  with  which  most 
chemists  have  had  to  deal  at  one  time  or  another 
during  their  career  :  what  is  the  place  of  the 
chemist  in  practical  life,  and  what  part  has  he 
taken  in  industrial  and  social  development  ? 

The  engineer  ministers  to  the  comfort  and 
convenience  of  the  community  in  ways  which 
can  hardly  escape  the  notice  even  of  the  man  in 
the  street.  The  Forth  Bridge,  the  ocean  grey- 
hound, the  motor  car  and  the  aeroplane  are  at 
once  recognised  as  the  fruits  of  his  skill  and  energy, 


viii  WHAT    INDUSTRY    OWES 

but  for  the  most  part,  the  work  of  the  chemist  is 
inobvious,  and  is  little,  if  at  all,  understood.  But 
the  chemist  and  his  half-brother,  the  metallurgist, 
have  all  the  time  been  hard  at  work  in  the  back- 
ground, helping  to  provide  the  engineer  with 
metals  and  other  ^materials  of  new  and  improved 
qualities,  without  which  he  could  not  have  produced 
the  machines  and  structures  which  represent  the 
triumphs  of  his  art. 

In  many  other  directions  chemistry  has  been 
the  handmaid  of  arts  and  crafts,  which  make 
their  appeal  to  the  public  on  far  other  grounds 
than  those  of  the  chemical  and  other  scientific 
help  they  have  laid  under  contribution. 

But  chemistry  also  has  its  own  triumphs,  and 
those  who  will  take  the  trouble  to  study  this  work 
will  be  rewarded  with  visions  of  achievement  in 
this  field  which  they  had  not  hitherto  dreamt  of. 

These  records  ought  to  prove  stimulating  and 
suggestive  to  those  whose  sons  and  daughters 
have  not  yet  selected  a  calling  or  profession.  The 
place  of  chemistry  in  the  national  life  has  been 
far  more  important  than  the  majority  of  educated 
people  have  imagined,  and  this  place  bids  fair  to 
become  of  vastly  increased  importance  in  the  near 
future.  The  special  message  for  parents  and 
teachers  is,  therefore,  that  trained  chemists  will, 
in  the  near  future,  be  in  increased  demand  for 
industrial  and  official  positions. 


TO    CHEMICAL    SCIENCE  ix 

For  the  responsible  teachers  of  chemistry  there 
are  other  messages  also,  if  they  care  to  seek  for 
them ;  for  from  these  records  of  achievement 
much  may  be  learned  as  to  the  actual  needs  of 
industry  on  its  scientific  side,  and  as  to  the  types 
of  workers  who  will  have  to  be  trained  if  these 
needs  are  to  be  properly  met. 

The  great  body  of  teachers  of  science  on  the  one 
hand,  and  the  still  greater  body  of  manufacturers 
on  the  other  hand,  have  been  equally  at  sea  as  to 
how  (a)  the  results  of  scientific  discovery,  and 
(6)  the  young  graduates  in  science  who  are  prepared 
at  our  universities  and  colleges,  can  best  be  utilised 
in  industry.  Speaking  broadly,  the  teachers  of 
science  do  not  know  the  needs  of  industry,  either 
in  regard  to  the  nature  of  the  problems  which 
await  solution,  or  to  the  kinds  of  trained  experts 
who  will  be  required  to  take  part  in  the  more 
highly  organised  industries  of  the  future.  Again, 
speaking  broadly,  manufacturers  and  leaders  of 
industry  are  equally  at  a  loss  as  to  the  means 
whereby  scientific  discovery,  scientific  methods  and 
scientifically  trained  men  can  be  used  most 
effectively  in  the  development  of  the  industries 
for  which  they  are  responsible. 

Fortunately,  there  are  already  lines  of  communi- 
cation open  between  these  two  important  bodies, 
and  the  hope  for  the  future  is  that  these  lines  may 
be  broadened  out  into  a  common  ground  on  which 


WHAT    INDUSTRY   OWES 


mutual  understanding  will  be  reached  and  where 
practical  schemes  of  development  will  be  developed. 
Much  can,  undoubtedly,  be  done  to  improve 
the  training  of  chemists  for  practical  life.  It  is  in 
the  laboratory  that  the  foundations  of  this  training 
must  be  well  and  truly  laid  by  sound  training  and 
ample  practice  in  manipulation  and  methods.  Not 
only  manipulative  skill,  but  resourcefulness  and  the 
power  of  organising  routine  work  ought  to  be 
acquired  in  the  laboratory,  if  the  training  is  on  the 
right  lines.  On  the  foundations  thus  laid,  a  super- 
structure of  knowledge  of  physical,  mechanical,  and 
chemical  laws  can  be  securely  built.  But  a 
scientific  equipment,  however  sound,  is  not  in 
itself  sufficient ;  it  is  of  equal  importance  that  the 
young  chemist  throughout  his  training  should  be 
thoroughly  imbued  with  the  spirit  and  aims  of  the 
successful  leaders  of  industry.  Nothing  will  so 
surely  awaken  in  the  student  an  appreciation  of 
practical  aims  as  a  wisely  directed  study  of  the 
achievements  of  science  in  industry.  The  present 
work  will  supply  teachers  of  chemistry  with 
abundant  material  for  the  purposes  of  this  study. 
This  study  ought  not,  however,  to  displace  the 
parallel  study  of  the  steps  by  which  chemical 
theory  has  been  evolved  by  the  deep  insight  and 
the  patient  observation  and  experiment  of  the 
great  leaders  in  chemical  science.  It  ought  to  be 
made  clear  to  the  student  that,  though  in  one  sense 


TO    CHEMICAL    SCIENCE 


the  two  aims,  the  attainment  of  knowledge  for  its 
own  sake,  and  its  attainment  as  a  means  to  practical 
ends,  are  at  opposite  poles,  yet  that  there  is  no 
real  antagonism  between  them,  each  is  com- 
plementary to  the  other.  There  are  intellectual 
triumphs  to  be  won  in  the  application  of  science 
as  well  as  in  its  pursuit  for  its  own  sake. 

The  deeper  and  more  prolonged  search  into  the 
phenomena  and  laws  of  Nature  must,  of  necessity, 
be  left  to  those  who  by  natural  endowment  and  by 
opportunity  can  pursue  this  search  apart  from 
the  distractions  of  the  work-a-day  world.  The 
workers  on  the  applications  of  science  may  well 
realise  their  debt  to  these  seekers  after  knowledge, 
for  the  seeds  of  achievement  on  the  practical  side 
must,  in  many  cases,  be  planted  and  watered  under 
their  fostering  care. 

During  the  past  three  years  the  scientific 
developments  of  modern  warfare  have  been  the 
means  of  bringing  the  workers  in  pure  and  in 
applied  science  into  touch  to  an  extent  which 
would  have  appeared  almost  impossible  in  pre-war 
times.  There  are  encouraging  evidences  that  this 
new  co-operation  has  been  appreciated  on  both 
sides,  and  that  a  return  to  the  former  condition  of 
isolation  would  be  regarded  as  most  unfortunate. 

The  authors  have  wisely  disclaimed  any  attempt 
in  this  work  to  present  the  extraordinary  wealth  of 
material  at  their  disposal  in  anything  like  its  true 


xii  WHAT    INDUSTRY    OWES 

proportions  and  perspective.  The  precious  stones 
in  the  necklace  have  been  strung  together  rather 
with  an  eye  to  their  collective  preservation  than 
to  their  artistic  effect  as  a  whole.  Apart  from  the 
reasons  for  this,  which  the  authors  themselves 
have  given,  I  am  inclined  to  think  that  for  the 
serious  purpose  they  had  in  view,  the  method  has 
much  to  commend  it.  The  central  object  was  not 
to  present  a  pleasing  and  finished  literary  work 
which  would  gently  stimulate  the  imagination  of 
the  general  reader,  but  to  set  forth  in  their  bare 
simplicity  the  broad  facts  of  achievement,  leaving 
each  case  to  make  its  own  appeal. 

In  conclusion,  I  would  express  the  hope  that 
this  work  will  not  only  be  widely  read  by  the 
general  public,  but  that  it  will  be  cordially  welcomed 
by  those  who  are  most  deeply  concerned  in  the 
future  of  British  industry. 

GEORGE  BEILBY. 


TO    CHEMICAL    SCIENCE  xiii 


PREFACE. 


IN  recent  times,  and  especially  during  the  war, 
a  great  deal  has  been  written  and  said  on  the 
benefits  derived  from  the  applications  of  science 
to  industry  ;  the  subject  has  been  discussed  in  the 
technical  and  daily  Press,  and  in  monographs 
devoted  to  particular  industries  ;  but,  for  the  most 
part,  it  has  been  dealt  with  in  the  abstract  or  with 
very  limited  reference  to  the  actual  results  achieved. 

The  contents  of  this  volume  appeared  as  a 
series  of  articles  published  in  The  Engineer  during 
the  seven  months  December,  1916,  to  July,  1917, 
inclusive,  under  the  title  of  "  What  Industry  Owes 
to  Science."  The  articles  were  not  intended  to 
embrace  subjects  of  common  knowledge  to  the 
engineer,  in  which  the  influence  of  physical  and 
mechanical  science  would  have  claimed  greater 
attention,  but  dealt  mainly  with  chemical  science. 
For  that  reason  the  title  of  the  work  has  been 
modified  ;  the  text,  however,  remains  piactically 
the  same. 

The  object  was  to  take  each  industry  in  turn, 
and  to  show  by  examples  how  science  had 
advanced  the  methods  and  processes  of  production 


xiv  WHAT    INDUSTRY   OWES 

and  had  laid  the  foundation  for  the  establishment 
of  new  manufactures. 

The  work  covers  a  survey  of  many  important 
industries,  presented  in  such  a  manner  that  the 
substance  is  not  altogether  out  of  the  depth  nor 
beyond  the  interest  of  the  educated  public.  We 
hope  that  it  may  be  especially  useful  to  students  of 
chemistry  and  engineering,  as  affording  them  an 
indication  of  the  vast  field  open  to  them  in  their 
professional  careers,  work  in  which  it  may  be 
anticipated  that  there  will  be  increasing  activity 
and  boundless  scope  in  the  near  future  ;  and  that 
it  will  find  a  place  in  the  offices  of  men  of  business 
in  many  branches  of  commerce,  and  of  public 
companies  concerned  with  productive  industries, 
as  well  as  in  the  libraries  of  Chambers  of  Commerce 
and  Trade  Associations. 

A  bibliography  is  provided,  including  many 
useful  books  referred  to  during  the  preparation 
of  the  work. 

The  authors  desire  to  express  their  deep  indebted- 
ness to  Sir  George  Beilby  for  his  kindness  in 
contributing  an  introduction,  which  they  feel  has 
very  greatly  enhanced  the  value  of  the  volume. 

R.  B.P. 
F.  B.-J. 
London,  1917. 


TO    CHEMICAL 


WHAT  INDUSTRY  OWES  TO 
CHEMICAL  SCIENCE. 

CHAPTER  I. 
MINERALS  AND  METALS. 

WE  have  heard  a  good  deal  lately  of  our  neglect 
of  science,  particularly  of  applied  science — and  we 
are  prepared  to  admit  that  this  country  has  been 
behind  other  countries  in  realising  the  importance  of 
scientific  principles  in  industry.  The  fact  remains, 
however,  that  though  we  have  been  so  remiss,  we  can- 
not have  ignored  science  entirely,  or  surely  the 
position  of  our  industries — those  that  are  left  to  us — 
to-day  would  not  be  what  it  is.  Instead  of  pursuing 
the  subject  in  the  abstract,  we  propose  in  a  few  brief 
chapters  to  deal  with  accomplished  facts  ;  to  show  by 
illustrative  examples  the  extraordinary  developments 
directly  attributable  to  scientific  thought  and  method 
and  the  benefits  derived  therefrom  by  the  community. 
The  whole  art  of  engineering  is  based  on  physical 
and  mechanical  science,  and  the  materials  employed 
in  this  art  are  dependent  in  some  degree  on  the 
science  of  chemistry.  This  country  has  never  lacked 
engineers  of  the  first  order,  and,  therefore,  if  we  may 
judge  by  their  works,  we  must  conclude  that  their 
science  has  been  as  truly  founded  as  their  structures, 
and  their  materials  must  likewise  have  been  suitable 
for  their  purpose.  Clearly,  then,  we  have  not  been 
lacking  the  aid  of  physicists,  mathematicians,  and 
chemists  in  the  art  of  engineering  and  all  that  the 
term  denotes.  The  materials  of  construction  cannot 
be  used  intelligently  unless  the  engineer  has  a  proper 


'WHAT   INDUSTRY   OWES 


knowledge  of  their  physical  powers  of  withstanding 
stress  and  strain,  as  well  as  of  their  chemical  proper- 
ties, including  their  internal  structure  and  power  of 
resistance  to  air,  fire,  water,  and  other  agencies. 

The  subject  is  so  vast  and  its  ramifications  so  diverse 
that  it  is  difficult  to  deal  with  it  without  being  drawn 
into  the  production  of  a  text-book,  but  we  will 
endeavour  to  keep  to  the  principal  aim  of  showing  the 
influence  of  science  in  industrial  progress. 

Our  methods  of  utilising  science  may  be  wrong, 
and  there  may  be  room  for  great  improvement, 
but  the  impression  is  gaining  ground  that  in  the 
habit  of  decrying  ourselves  and  our  doings  we  have 
overshot  the  mark.  We  have  used  science  more 
than  we  realise,  but  have  not  talked  about  it  as  much 
as  some  other  people.  We  know,  for  instance, 
several  Sheffield  steel  firms  who  employ  thirty  to  forty 
chemists  and  are  in  constant  touch  with  the  most 
experienced  men  of  science  interested  in  this  branch 
of  industry.  We  know  also  that  both  in  the  direc- 
torate and  in  the  control  of  the  actual  processes 
of  manufacture  in  the  works  the  industry  is  coming 
more  and  more  under  the  personal  supervision  of 
scientific  men,  that  new  laboratories  are  being 
equipped,  and  that  science  in  the  steel  industry  is 
now  very  much  to  the  fore. 

STEEL. 

German  delegates  to  the  meeting  of  the  Iron  and 
Steel  Institute  held  at  Sheffield  in  1905,  freely 
admitted  that  Germany  had  much  to  learn  from  that 
centre  and  no  doubt  derived  benefit  from  the  hos- 
pitality then  extended  to  them.  The  reputation  of 
Sheffield  in  steel  production  dates  from  1740, 
when  Huntsman  discovered  the  process  of  casting 
completely  fused  rnetal  from  crucibles.  Sixty 
years  ago  steel  was  obtained  by  decarburising  pig 
iron  to  malleable  iron  in  a  puddling  furnace  and 
subsequently  introducing  the  requisite  amount  of 
carbon  by  the  cementation  process.  These  operations 
were  protracted,  required  exhausting  labour,  and 
involved  the  use  of  large  and  expensive  furnaces 


TO    CHEMICAL    SCIENCE  3 

subjected  to  considerable  wear  and  tear  and  consuming 
large  quantities  of  fuel. 

In  1856,  Bessemer — a  scientific  man — as  the  result 
of  experiments  deliberately  directed  to  a  definite 
object,  introduced  his  process  for  *'  The  Preparation 
of  Steel  without  Fuel."  He  found  that  by  forcing 
a  blast  of  atmospheric  air  through  molten  cast  iron, 
contained  in  a  suitable  vessel  lined  with  ganister, 
a  siliceous  material,  the  oxidisable  impurities  in  the 
iron  could  be  removed  without  the  external  applica- 
tion of  heat,  since  the  heat  produced  by  oxidation 
was  sufficient  to  keep  the  mass  in  a  molten  state. 
Manual  or  mechanical  stirring  was  unnecessary.  The 
pig  was  melted  in  a  cupola,  and  transferred  to  a  mixer 
of  up  to  600  tons  capacity.  From  the  mixer  a  charge 
was  conveyed  by  a  ladle  to  the  converter,  the  latter 
being  swung  into  position  after  the  "  blow  "  had  been 
started.  In  twenty  minutes  the  operation  was 
completed  ;  the  blast  was  stopped  for  a  few  seconds 
while  a  workman  threw  in  from  a  shovel  sufficient 
spiegel  or  ferro-manganese  to  introduce  the  proper 
proportions  of  carbon  ;  the  blast  was  started  again 
for  a  short  time  to  mix  the  metal  and  the  charge  was 
immediately  poured  into  moulds. 

Contrast  the  rapidity  and  simplicity  of  this  method 
with  the  time  and  labour  expended  in  the  other. 
Cementation  alone  required  seven  to  ten  days  ;  the 
equivalent  effect,  after  Bessemerisation,  occupies  only 
the  time  required  to  add  the  spiegel  and  re -mix  the 
charge.  The  fuel  expended  is  only  that  used  in  the 
cupolas,  and  even  that  is  obviated  in  some  cases  where 
the  constancy  of  grade  of  pig  from  the  blast-furnaces 
can  be  relied  on,  when  the  pig  is  taken  direct  from  the 
blast-furnace  to  the  converter. 

The  original  or  acid  Bessemer  process  had,  however, 
two  disadvantages: — (1)  phosphorus  and  sulphur 
could  not  be  removed  owing  to  the  reduction  of  their 
oxides  by  iron  and,  therefore,  only  special  "  Bessemer 
pigs,"  free  from  phosphorus  and  very  low  in  sulphur, 
could  be  used  ;  (2)  the  ingots  produced  contained 
blow-holes.  Science  overcame  the  first  of  these 
disadvantages.  In  1879  Thomas  and  Gilchrist  found 

B 


WHAT    INDUSTRY    OWES 


that  by  lining  a  converter  with  burnt  dolomite  or 
magnesite,  instead  of  ganister,  and  by  adding  a 
quantity  of  lime  to  the  charge,  the  whole  of  the 
phosphorus  and  some  of  the  sulphur  could  be  removed. 
This  was  the  result  not  only  of  scientific  methods 
of  research  but  of  the  direct  application  of  a  scientific 
principle,  viz.,  that  of  using  a  basic  lining  and  adding 
lime,  a  basic  material,  to  retain  the  acidic  substances 
produced  by  the  oxidation  of  phosphorus  and  sulphur. 
The  second  problem,  however,  was  solved  by  the 
empirical  discovery  that  the  addition  of  a  very  small 
quantity — 5  to  8  oz.  per  ton — of  aluminium  to  the 
molten  metal  minimised  the  formation  of  blow -holes. 
The  only  important  rival  to  the  Bessemer  method  is 
the  open-hearth  process,  perfected  about  twelve  years 
later  by  Sir  William  Siemens  and  his  brother — both 
scientific  men.  After  great  initial  difficulties,  they 
succeeded  in  decarburising  iron  without  contact  with 
solid  fuel.  In  this  process  an  exceedingly  high 
temperature  is  produced  in  an  oxidising  atmosphere 
by  the  combustion  of  a  mixture  of  producer  gas  and 
air  fed  into  the  furnace.  Changes  take  place  of  the 
same  character  as  in  the  Bessemer  process.  Both 
acid  and  basic  hearths  are  used,  and  the  principle  of 
regenerative  heating  is  utilised. 

To  Dr.  Sorby,  of  Sheffield,  we  owe  the  introduction 
of  metallography,  and  in  this  connection  the  names 
of  Osmond,  Martens,  Stead,  Roberts-Austen,  Sauveur, 
and  Le  Chatelier,  all  men  of  science,  must  be  remem- 
bered. Up  to  the  present  day,  and  for  some  years  past, 
the  miscroscopic  examination  of  the  etched  surfaces  of 
metal  has  been  common  practice  in  steel  works  labora- 
tories. Researches  on  the  cause  of  recalescence,  com- 
bined with  the  intimate  knowledge  of  the  structure  of 
steels  afforded  by  miscroscopic  examination,  have 
placed  in  the  clear  light  the  equilibrium  relations  of 
iron  and  carbon,  and  have  thus  changed  rule-of -thumb 
experience  into  sound  scientific  principle.  Our  views 
on  the  physical  and  chemical  nature  of  these  equili- 
brium relations  have  been  changed  by  the  progress  of 
research.  Explanation  by  means  of  the  solution  theory 
has  replaced  that  based  on  the  theory  of  the  allotropy 


TO    CHEMICAL    SCIENCE 


of  iron,  and  our  knowledge  of  the  subject  is  thus  be- 
coming more  definitely  established.  To  be  able  to  ex- 
plain a  phenomenon  is  second  only  to  knowing  that 
the  phenomenon  will  occur.  Whereas  rule -of -thumb 
or  empirical  discoveries  may  occasionally  give  us  good 
results,  science,  organised  knowledge,  enables  us  to 
proceed  on  definite  lines. 

The  discovery  of  rarer  metals  has  led  to  the  manu- 
facture of  many  varieties  of  steel,  including  alloys  of 
special  hardness.  The  properties  of  special  steels 
and  their  behaviour  under  varying  conditions,  the 
bearing  of  the  character  of  their  internal  structure 
and  similar  questions  have  formed  the  basis  of 
numerous  researches  which  have  rendered  the  in- 
dustry in  an  increasing  degree  more  exact  and 
scientific.  The  researches  of  Sir  Robert  Hadfield 
have  resulted  in  supplying  us  with  special  steels 
differing  from  ordinary  steels,  through  the  addition 
of  various  elements  other  than  those  commonly 
present,  whereby  they  acquire  properties  of  enhanced 
hardness,  toughness,  elasticity,  &c. 

Thus,  by  adding  7  to  20  per  cent,  of  manganese  we 
ensure  great  strength  and  toughness,  the  well-known 
Hadfield  steel  ordinarily  containing  about  13' per  cent, 
of  manganese  and  1  per  cent,  of  carbon  ;  the  addition 
of  about  3  per  cent,  of  nickel  and  0.2  per  cent,  carbon 
gives  us  a  steel  of  tensile  strength  and  elasticity  suit- 
able for  the  manufacture  of  gun  barrels  ;  and  the 
addition  of  2  to  3  per  cent,  of  chromium  with  about 
1  per  cent,  of  combined  carbon  gives  a  remarkable 
steel  which,  when  hardened  and  tempered,  is  employed 
in  the  manufacture  of  locomotive  tires  and  springs, 
armour  plates,  armour-piercing  projectiles,  and  certain 
qualities  of  files.  Similarly,  the  introduction  of 
titanium,  molybdenum,  tungsten,  aluminium,  vana- 
dium, and  boron  gives  varying  effects  now  easily 
obtainable  by  the  scientific  steel  maker. 

These  examples  serve  to  illustrate  clearly  the 
advantages  gained  by  the  application  of  scientific 
knowledge  in  the  production  of  one  of  our  chief 
materials  ;  but  the  function  of  the  chemists  in  a  steel 
works  or  any  works  is  not  confined  to  devising  pro- 

B  2 


6  WHAT   INDUSTRY    OWES 

cesses  or  producing  varieties  of  the  products.  They 
are  concerned  with  problems  of  many  kinds,  and 
among  these  the  question  of  fuel  and  fuel  economy 
both  in  raising  power  and  in  smelting  operations  are 
of  primary  importance.  Science  determines  the 
suitability  and  value  of  the  coal  employed.  Tests  are 
made  to  determine  the  calorific  power  and  to  estimate 
the  sulphur,  ash,  and  the  volatile  matter,  including 
moisture,  all  important  factors  from  the  point  of  view 
of  economy.  The  manufacturer  who  ignores  these 
questions  must  suffer  through  the  employment  of  coal 
containing  sulphur  which  attacks  his  fire-boxes,  and 
the  purchase  of  water  and  useless  mineral  matter. 
Next,  the  treatment  of  boiler-feed  water  where  the 
supply  is  not  naturally  soft  must  not  be  neglected,  or 
the  accumulation  of  scale  will  result  in  waste  of  heat, 
inefficient  working,  and  other  deplorable  conditions. 
The  method  of  water  softening,  by  the  addition  of 
lime,  was  established  by  Dr.  Thomas  Clark,  Professor 
of  Chemistry  at  Aberdeen  University,  from  1833-39, 
and  its  importance  in  every  industry  involving  the  use 
of  boilers,  or  requiring  the  use  of  soft  water,  must 
have  been  and  still  is  inestimable. 

NON-FERROUS  METALS. 

Mining  and  metallurgical  industries  are  essentially 
scientific,  calling  for  the  services  of  chemists  (1)  on 
the  mines,  to  examine  ores,  to  advise  on  their  concen- 
tration and  generally  to  specify  the  methods  to  be 
adopted  for  the  extraction  of  metals,  and  (2)  in  the 
actual  working  of  the  metal. 

The  production  of  non-ferrous  metals,  such  as 
copper,  lead,  zinc  and  aluminium,  needs  the  help  of 
trained  technologists  whose  labours  are  constantly 
directed  to  the  discovery  of  improved  processes  and  of 
new  varieties  of  alloys  adapted  to  special  purposes, 
particularly  those  demanded  by  the  trend  of  engineer- 
ing development. 

In  surveying  the  history  of  non-ferrous  metallurgy, 
the  most  striking  feature  is  the  extent  of  comparatively 
recent  scientific  advancement.  In  many  cases  the 
methods  of  treating  ores  to  obtain  crude  metal 


TO    CHEMICAL    SCIENCE 


remain  fundamentally  the  same  as  when  they  were 
originally  discovered — for  the  most  part  empirically  ; 
but  they  have  been  explained,  modified,  and  improved 
by  science  ;  while  in  other  cases,  new  and  better 
methods,  due  solely  to  science,  have  been  substituted 
for  old  ones. 

The  Separation  of  Minerals. — The  ores  of  heavy 
metals  are  frequently  of  such  low  grade  that  the 
metal  cannot  be  won  economically.  Thousands 
of  tons  of  valuable  minerals  would  still  remain 
unworked  except  for  the  scientific  methods  of  con- 
centration now  employed.  An  ore  containing  only 
one  per  cent,  of  tin  will  repay  treatment. 
It  cannot  be  smelted,  but  a  complex  process 
of  table  washing,  roasting,  and  washing  again  con- 
centrates it  to  60  to  70  per  cent,  ready  for  the 
smelter.  Low  grade  sulphide  ores  and  graphite 
ores  are  concentrated  by  one  or  other  of  various 
methods  of  oil  separation  and  flotation  which  afford 
interesting  examples  of  discovery  originated  in 
empiricism,  developed  by  chance  discovery  and 
mechanical  ingenuity  and  further  improved  by  the 
direct  application  of  scientific  thought,  whereby  their 
utility  has  become  widely  extended  so  as  to  effect 
invaluable  economies  in  the  mineral  industries. 
Although  various  theories  have  been  advanced  to 
explain  the  phenomena  of  flotation,  the  true  mechan- 
ism remains  as  yet  obscure.  It  is  instructive  to 
follow  the  stages  of  the  advances  made  in  this  direc- 
tion, and  to  indicate  the  present  views  on  the  subject. 

In  1886  Carrie  J.  Everson  found  that  sulphide 
mineral  particles  could  be  separated  from  the  gangue 
in  ores  by  kneading  the  finely  crushed  ore  with  a  paste 
formed  by  the  action  of  sulphuric  acid  on  certain 
oils,  e.g.,  linseed  or  cotton  seed.  The  oil  adhered  to 
the  particles  of  sulphide  mineral  and  bound  the  whole 
into  a  coherent  mass.  The  gangue  was  then  washed 
away  by  water.  The  process  was  very  little  used,  its 
application  being  limited  to  rich  pyritic  gold  ores, 
the  treatment  of  which  was  profitable. 

The  next  development,  patented  by  Elmore  in  1898, 
was  an  oil  separation  process  wherein  the  finely 


8  WHAT    INDUSTRY   OWES 

crushed  sulphide  ore  made  into  a  pulp  with  water 
was  well  mixed  with  3  to  6  per  cent,  of  its  weight 
of  residuum  oil.  The  oil  floated  to  the  top  and 
formed  a  layer  carrying  the  sulphides,  leaving  behind 
the  gangue.  The  top  layer  was  separated  by  means 
of  a  spitzkasten  and  the  oil  run  into  a  centifrugal 
machine  containing  warm  water,  where  some  of  the 
oil  was  separated  to  be  used  over  again.  The  partially 
de -oiled  concentrates  were  further  treated  in  a  smaller 
centifrugal  to  effect  a  further  separation  of  oil,  and 
were  then  ready  for  the  smelter.  In  1901  Elmore 
patented  the  use  of  sulphuric  acid  in  the  process,  as 
an  aid  to  the  production  of  cleaner  concentrates. 
The  process  was  not  generally  adopted  because  the 
losses  of  oil  due  to  entanglement  in  the  gangue  pulp 
were  very  high. 

The  Elmore  vacuum  method  was  an  outcome  of 
the  above.  This  is  an  oil  flotation  process,  as  distinct 
from  an  oil  separation  process.  The  pulp  of  ore  and 
water,  mixed  with  a  very  small  quantity  of  oil  and 
enough  sulphuric  acid  to  make  the  mixture  slightly 
acid,  is  exposed  to  a  partial  vacuum ;  the  air 
dissolved  in  the  water  rises  up  through  it  in  the  form 
of  bubbles,  floating  the  oiled  sulphides  to  the  top, 
whence  they  are  drawn  off.  From  a  2  to  3  per  cent, 
copper  ore,  concentrates  of  up  to  20  per  cent,  can 
be  produced. 

In  1901  C.  V.  Potter,  working  on  Broken  Hill  ore, 
heated  the  crushed  ore  in  an  acid  water  pulp.  The 
action  of  the  acid  upon  carbonates  in  the  ore  generated 
carbonic  acid  gas,  which,  rising  to  the  top,  carried 
sulphide  mineral  with  it.  In  1902,  in  connection  with 
this  process,  G.  D.  Delprat  used  salt  cake  instead  of 
sulphuric  acid. 

In  1903  Cattermole,  by  adding  4  to  6  per  cent, 
of  oleic  acid  to  the  ore -water  pulp  and  applying  slow 
agitation,  caused  the  sulphide  particles  to  aggregate 
into  large  granules  with  the  oil.  The  gangue  which 
remained  in  the  pulp  was  then  separated  by  means 
of  an  up -cast.  The  principle  of  the  method  was  good, 
but  the  expense  in  oil  was  large.  It  was  in  connection 
with  the  work  on  this  process,  however,  that  the  froth 


TO    CHEMICAL    SCIENCE  9 

flotation  process  was  discovered.  By  using  small  quan- 
tities of  oil — up  to  0. 1  per  cent,  calculated  on  the  ore, 
though  less  generally — and  churning  up  the  pulp  with 
air  by  rapid  agitation  with  a  special  paddle,  the  oiled 
sulphide  particles  are  caused  to  rise  to  the  top  as  a 
strong  froth  which  is  floated  off  by  a  spitzkasten.  This 
process  especially  has  been  developed  by  scientific  re- 
search, and  the  efficiency  and  the  economy  of  ore  con- 
centration have  been  thereby  greatly  improved.  Sul- 
phide ores  of  zinc,  copper,  lead,  iron,  antimony, 
molybdenum,  and  of  other  metals  are  very  efficiently 
treated.  Tin -stone -pyrites  table  concentrates  are 
separated,  the  pyrites  being  floated  off ;  and  graphite 
is  easily  concentrated  to  an  exceedingly  clean  product. 
The  grade  of  the  concentrates  is  high  and  the  recovery 
excellent.  The  use  of  acid  is  sometimes  necessary 
to  produce  clean  concentrates,  enough  being  added 
to  ensure  an  acid  reaction  in  the  pulp.  Curves  can  be 
plotted  showing  the  variations  hi  grade  of  concen- 
trates and  recovery  with  variation  in  the  amounts  of 
oil  and  acid  used.  The  testing  of  ores  is  scientifically 
carried  out  in  special  apparatus.  The  experimenter 
not  only  finds  the  best  method  for  treating  the  ore, 
but  also  observes  and  records  any  peculiarities  ex- 
hibited that  may  be  of  use  in  furthering  the  aims  of 
the  process  or  may  serve  to  throw  light  on  the 
ultimate  causes  of  the  principles  underlying  the 
method.  Wood's  modification  of  the  above  process 
renders  it  possible  to  concentrate  certain  ores  without 
the  use  of  oil. 

These  concentration  processes  are  of  comparatively 
recent  invention,  and  are  increasingly  applied  to  the 
treatment  of  low  grade  sulphide  ores  and  the  tailings 
from  table  concentrations. 

Experiments  on  the  flotation  of  other  minerals, 
such  as  native  copper,  gold,  and  Scheelite,  an  ore  of 
tungsten,  have  met  with  success,  and  will  probably 
be  greatly  developed  during  the  next  few  years.  The 
flotation  of  carbonate  and  other  oxidised  ores  has 
been  attempted  with  positive  results,  but  this  exten- 
sion also  is  as  yet  in  the  experimental  stage.  The 
general  opinion  of  men  of  science  at  the  present  day 


10  WHAT    INDUSTRY    OWES 

is  that  flotation,  is  an  effect  of  surface  tension,  though 
some  favour  the  view  that  the  mineral  particles  must 
also  carry  an  electric  charge.  The  ultimate  causes 
can  only  be  established  by  further  research. 

In  dealing  with  the  separation  of  minerals  we  should 
mention  also  the  important  work  of  electrical  and 
mechanical  engineers,  to  whom  much  credit  is  due  for 
the  invention  of  magnetic  separators.  Many  ores 
containing  magnetic  minerals  are  now  efficiently 
treated  by  these  machines,  involving  both  wet  and  dry 
methods.  As  instances  may  be  taken  the  magnetic 
concentration  of  magnetite  ores,  and  the  separation 
of  this  mineral  from  pyrites.  Magnetic  separation 
has  also  been  applied  in  the  treatment  of  monazite 
sands  for  the  concentration  of  thorium,  to  which  we 
will  refer  later. 

Copper. — Scientific  knowledge  has  come  to  the  aid 
of  the  copper  smelter  and  refiner  in  various  ways.  The 
introduction  of  water -jacketed  blast  furnaces — such 
as  are  used  in  lead  smelting — in  the  fusion  for  regulus, 
has  reduced  wear  and  tear  to  the  minimum.  These 
furnaces  are  made  of  iron  and  are  double  walled,  with 
water  circulating  through  the  space  between  the 
walls,  producing  a  cooling  effect  inside  the  furnace  in 
the  immediate  vicinity  of  the  wall.  The  result  is 
that  some  of  the  molten  slag  solidifies  on  the  wall, 
forming  a  protective  coating  which  is  not  further 
attacked,  since  the  liquid  does  not  corrode  it,  and 
thus  the  iron  walls  of  the  furnace  scarcely  come  into 
contact  with  the  liquid. 

A  method  of  smelting  pyritic  copper,  silver,  or  gold 
ores  by  the  heat  of  oxidation  of  the  pyrites,  without 
the  aid  of  any  other  fuel  was  introduced  as  recently 
as  1905  ;  in  actual  practice,  however,  up  to  5  per  cent, 
of  carbonaceous  fuel  is  now  added.  Water-jacketed 
blast  furnaces  are  used,  and  air — pre-heated  in  some 
cases — is  liberally  supplied  through  a  large  number 
of  tuyeres. 

Copper  intended  for  use  as  an  electrical  conductor 
must  be  of  high  quality,  the  presence  of  very  small 
quantities  of  certain  other  bodies  causing  a  marked 
diminution  in  its  efficiency.  The  necessary  degree  of 


TO    CHEMICAL    SCIENCE  11 

purity  can  now  easily  be  obtained  by  the  methods  of 
electrolytic  refining.  A  thin  sheet  of  electrolytic 
copper  forms  the  cathode,  a  slab  of  blister  copper 
the  anode,  and  the  electrolyte  is  an  acidified  solution 
of  copper  sulphate. 

Pure  copper  is  deposited  on  the  cathode,  the  anode 
being  gradually  dissolved.  Impurities  in  the  copper, 
such  as  iron,  zinc,  nickel,  &c.,  of  which  the  sulphates 
are  soluble,  are  allowed  to  accumulate  in  the  solution 
until  their  quantity  renders  the  liquor  inconvenient 
to  deal  with.  At  this  stage  the  copper  in  the  liquor 
is  precipitated  with  metallic  iron  and  fresh  solution 
substituted.  Other  metals  present,  such  as  platinum, 
gold,  silver,  lead,  and  arsenic,  form  a  fine  mud  in  the 
bath,  and  this  mud  is  afterwards  treated  for  recovery 
of  the  precious  metals.  Thus,  by  this  scientific 
method,  not  only  is  copper  obtained  in  a  very  pure 
state,  but  the  gold,  silver,  and  platinum  also  can  be 
extracted  profitably. 

Lead. — A  remarkable  instance  of  the  application  of 
pure  science  to  the  solution  of  a  technical  problem  is 
provided  in  the  methods  employed  in  the  desilverisa- 
tion  of  lead  by  the  Pattinson  and  the  Parkes  methods. 
Before  1833  the  only  available  process  was  cupellation, 
and  this  could  only  be  effected  economically  if  the  lead 
contained  8  oz.  per  ton  or  more  of  silver.  Therefore 
much  silver  remained  in  the  lead,  of  which,  in  the 
aggregate,  large  quantities  contained  less  than  this 
amount.  The  method  patented  by  Hugh  Lee 
Pattinson  in  1833  depended  on  the  fact  that  when 
a  solution  is  partially  frozen  some  of  the  solvent 
separates  in  the  solid  form,  leaving  a  solution  richer 
in  the  dissolved  substance.  For  instance,  when  salt 
water  is  frozen,  pure  ice  separates  and  the  remaining 
solution  Is  stronger  in  salt.  Molten  lead  containing 
silver  may  be  regarded  as  a  solution  of  silver  in  lead, 
and  if  this  solution  is  allowed  to  solidify  partially, 
almost  pure  lead  separates  out  in  crystals.  Two 
methods  are  adopted,  that  of  thirds  and  that  of 
eighths.  Usually,  sixteen  kettles,  lined  with  lime  to 
prevent  attack  by  litharge  and  holding  about  12  tons 
each,  are  employed.  For  lead  comparatively  rich  in 


12  WHAT   INDUSTRY   OWES 

silver,  two-thirds  of  the  contents  of  each  pot  are 
removed  as  lead  crystals  ;  and  for  lead  which  is 
poorer  in  silver,  seven-eighths  of  the  contents  is 
removed  from  each  pot.  In  the  latter  case  fewer 
pots  are  required.  By  these  means,  respectively, 
starting  from  a  lead  containing  up  to  3  oz.  of  silver 
per  ton,  a  silvery  lead  containing  700  oz.  per  ton, 
and  a  "  pure  "  lead  containing  only  £  oz.  to  £  oz.  of 
silver  per  ton  can  be  obtained.  The  process  in  each 
case  is  stopped  when  the  silver  reaches  about  700  oz. 
per  ton,  as  this  is  approaching  the  eutectic.*  A 
modification  of  the  method  nas  been  introduced 
whereby  the  lead  is  cooled  more  quickly  by  blowing 
in  steam  and  spraying  the  top  of  the  lead  with  cold 
water,  the  rich  silvery  lead  being  poured  off  from  the 
crystals  instead  of  the  latter  being  baled  out. 

The  silvery  lead  obtained  by  either  process  is 
cupelled  on  a  hearth  made  partially  of  bone  ash, 
which  absorbs  most  of  the  lead  oxide.  Some  of  the 
litharge  produced  is  blown  over  the  side  of  the  cupel 
by  the  blast  of  air,  and  is  used  in  the  manufacture  of 
paint. 

The  Parkes  process  depends  upon  the  fact  that 
silver  is  much  more  soluble  in  zinc  than  it  is  in  lead, 
whilst  lead  and  zinc  are  mutually  soluble  only  to  a 
small  extent.  A  saturated  solution  of  zinc  in  lead 
contains  only  about  1  per  cent,  of  zinc  whilst  a 
saturated  solution  of  lead  in  zinc  contains  2  to  3  per 
cent,  of  lead.  If,  therefore,  molten  argentiferous  lead 
is  stirred  up  with  molten  zinc  the  latter  extracts  most 
of  the  silver  from  the  lead  and  when  the  stirring  is 
discontinued  rises  to  the  top,  forming  a  separate  layer. 
An  exactly  parallel  operation  frequently  used  in  the 
laboratory  is  the  method  of  extraction  by  ether. 
On  shaking  ether  and  water  together  each  dissolves  a 
little  of  the  other.  When  the  shaking  is  stopped  the 
liquids  separate  into  two  layers,  the  ether  being  the 
uppermost.  Suppose  we  are  dealing  with  the  aqueous 
solution  of  a  substance  that  is  more  soluble  in  ether 
than  in  water,  and  that  the  solution  in  water  is 
inconvenient  to  work  with,  the  substance  can  be 

*  See  note  on  p.  21. 


TO    CHEMICAL    SCIENCE  13 

almost  completely  removed  as  a  solution  in  ether  by 
shaking  the  solution  repeatedly  with  small  quantities 
of  ether,  which  can  then  be  removed  by  distillation. 

In  practice,  the  work  lead  is  purified  by  remelting, 
to  effect  the  removal  of  copper,  arsenic,  antimony,  &c. 
The  lead,  so  far  purified,  is  then  melted  in  a  pot 
and  heated  to  about  500  deg.  C.,  lumps  of  zinc  are 
added  and  the  liquid  is  well  stirred  with  iron  paddles. 
The  quantity  of  zinc  added  depends  on  the  richness 
of  the  lead  in  silver,  but  in  any  case  is  very  small  and 
rarely  exceeds  2  per  cent,  of  the  weight  of  the  lead. 
When  the  agitation  is  stopped,  the  liquid  is  allowed  to 
cool  and  a  crust  of  zinc  containing  the  silver  solidifies 
on  top  of  the  still  molten  lead,  is  removed  by  ladles 
and  liquated  to  separate  some  of  the  zinc.  The 
remainder  of  the  zinc -silver  mixture  is  then  transferred 
to  graphite  retorts  and  the  zinc  is  distilled  off.  It  is 
found  to  be  advantageous  in  extraction  by  zinc — as  in 
the  case  of  ether — to  add  the  zinc  in  three  instalments, 
and  not  all  at  once.  When  the  lead  contains  gold, 
about  one-tenth  of  the  zinc  is  put  in  at  first,  when  the 
scum  of  zinc  separated  contains  all  the  gold.  The 
silver  is  then  extracted  by  continuing  the  process. 
The  remaining  lead  contains  about  1  per  cent,  of 
zinc,  which  is  removed  by  blowing  air  and  steam 
through  the  molten  metal,  the  zinc  being  blown  away 
as  oxide,  leaving  the  lead  in  a  very  pure  state.  The 
Parkes  process,  now  used  extensively,  has  been 
rendered  more  efficient  by  the  recent  discovery  that 
graphite  retorts  can  be  used  for  the  distillation  of  the 
zinc. 

These  processes  for  desilverisation  not  only  yield 
valuable  quantities  of  silver  but  also  produce  lead 
in  a  high  state  of  purity.  In  fact,  lead  as  now  pro- 
duced is  one  of  the  purest  of  the  commercial  metals. 
It  would  probably  not  be  so  if  no  precious  metal 
could  be  extracted  from  it,  because  in  order  to  win 
the  silver  all  other  impurities  must  also  be  removed. 
Whereas  work  lead  is  hard,  pure  lead  is  soft  and  can 
be  easily  manipulated,  purity  being,  moreover,  very 
important  in  the  starting  material  for  the  manufac- 
ture of  white  lead  for  making  paint. 


14  WHAT    INDUSTRY    OWES 

Nickel  was  discovered  by  Cronstedt  in  1750- 
During  recent  years  it  has  assumed  an  important 
position  in  the  civilised  world.  It  is  malleable, 
ductile,  hard,  takes  a  high  polish,  and  is  very 
resistant  to  atmospheric  oxidation.  To  these 
valuable  properties  nickel  owes  its  use  in  the  electro- 
plating of  small  iron  and  steel  articles  to  prevent 
rusting,  in  the  manufacture  of  rifle  bullets,  which  are 
covered  with  a  layer  of  nickel  to  give  a  hard  clean 
surface  that  will  not  foul  the  barrel,  and  also  in  the 
preparation  of  nickel  steels  and  of  certain  alloys 
with  copper  and  zinc,  such  as  nickel  silver,  which 
are  used  in  the  manufacture  of  forks  and  spools, 
ornamental  articles,  wire,  medals,  and  coins.  Nickel 
is  also  used  in  the  finely  divided  state  as  a  catalyst, 
in  the  hydrogenation  of  certain  oils  and  fats.  By  the 
action  of  hydrogen  in  the  presence  of  finely  divided 
nickel,  liquid  oils  such  as  fish  oil,  linseed  oil,  olive  oil, 
can  be  "  hardened  "  into  solid  fats  suitable  for  the 
starting  materials  in  the  manufacture  of  foodstuffs, 
candles,  and  soap.  For  these  purposes  the  nickel 
used  must  be  very  pure.  The  older  methods  of  pro- 
duction were  difficult  and  expensive,  but  in  1895 
Ludwig  Mond  introduced  a  method  by  which  the 
pure  metal  can  be  obtained  at  a  comparatively  low 
cost  from  the  matte  produced  by  the  first  smelting 
operation.  Mond  discovered  that  metallic  nickel 
combines  with  carbon  monoxide  when  heated  to 
80  deg.  C.  in  an  atmosphere  of  that  gas,  yielding 
a  volatile  compound,  nickel  carbonyl.  The  matte  is 
roasted  and  then  reduced  at  400  deg.  C.  by 
producer  gas.  The  reduced  metal  is  then  exposed 
at  80  deg.  C.  in  a  "  volatiliser "  to  the  action  of 
carbon  monoxide.  The  gas  issuing  from  the  volatiliser 
containing  the  nickel  carbonyl  is  passed  through 
vessels  heated  to  180  deg.  C.,  where  the  nickel  is 
deposited  in  the  pure  state.  The  carbon  monoxide 
is  obtained  from  flue  gases  by  passing  first  through 
boiling  potassium  carbonate  solution  and  then  over 
hot  coke.  The  carbon  monoxide  obtained  by  the 
decomposition  of  the  nickel  carbonyl  at  180  deg.  C. 
is  also  used  over  again.  This  brief  survey  shows  how 


TO    CHEMICAL    SCIENCE  15 

Mond's  scientific  discovery  and  its  exploitation  has 
had  its  effect  on  very  diverse  industries. 

Sodium. — Metallic  sodium  was  first  obtained  by  Sir 
Humphry  Davy,  in  1807,  by  the  electrolysis  of  caustic 
soda,  but  no  attempt  was  then  made  to  manufacture 
sodium  on  the  large  scale  by  that  process.  Up  to  1891 
it  was  produced  by  carbon  reduction  methods.  The 
method  of  Brunner,  improved  by  Deville,  consisted  in 
igniting  a  mixture  of  sodium  carbonate  and  charcoal ; 
but  this  process  was  very  wasteful  and  expensive, 
and  the  price  of  sodium  was  consequently  high. 
In  1886  Castner  employed  caustic  soda  instead  of 
sodium  carbonate,  and  this  improvement,  the  outcome 
of  scientific  research,  effected  substantial  decrease  in 
the  cost  of  production.  In  1891  the  old  process  was 
entirely  abandoned  and  replaced  by  Castner's  electro- 
lytic method,  founded  on  Davy's  discovery  and 
developed  in  the  laboratory,  by  which  fused  caustic 
soda  was  electrolysed  in  an  iron  vessel  under  special 
precautions  for  even  heating  and  the  maintenance  of 
a  constant  temperature.  The  method  was  cleaner 
and  more  efficient,  and  as  a  result  sodium  became  really 
a  commercial  product,  thousands  of  tons  being  ren- 
dered available  annually  for  the  preparation  of  sodium 
cyanide  for  gold  extraction,  under  the  MacArthur- 
Forrest  process  for  dealing  with  low  grade  ores  and 
sand  and  slime  tailings. 

Aluminium — so  much  valued  for  its  lightness, 
strength,  and  unalterability  in  air — has  a  history 
resembling  that  of  sodium.  It  was  first  isolated  in  the 
pure  state  in  1827  by  Wohler  by  fusing  the  chloride 
of  the  metal  with  potassium  in  a  closed  crucible,  and 
again  by  the  same  chemist  by  passing  the  vapour  of 
aluminium  chloride  over  potassium.  In  1854  Bunsen 
used  the  method  of  electrolysis  of  the  fused  chloride, 
and  Deville  applied  the  method  of  Wohler  in  attempts 
to  manufacture  the  metal  on  a  large  scale  using 
sodium  instead  of  potassium.  Samples  of  Deville's  pro- 
ducts were  shown  in  ingots  at  the  Paris  Exhibition  of 
1855,  where  they  occupied  a  prominent  position,  care- 
fully guarded  by  gendarmes,  only  a  few  visitors  being 
allowed  to  handle  the  exhibit,  which  was  regarded  as 


16  WHAT    INDUSTRY    OWES 

a  great  curiosity.  This  was  an  incentive  to  further 
research,  with  the  result  that  a  short  time  later  the 
large  scale  manufacture  was  established  at  Alais  on 
the  Loire.  The  use  of  sodium,  then  itself  a  costly 
metal,  was  only  one  item  in  the  heavy  expense 
involved.  The  method  held  its  own  for  some  years, 
but  in  1887  Bernard  Freres,  of  Paris,  reverting 
to  the  method  of  Bunsen,  founded  their  electro- 
lytic process,  using  a  mixture  of  cryolite  and 
common  salt  as  the  electrolyte.  Before  1887 
aluminum  was  sold  at  £3  per  pound.  Now  it  can  be  made 
at  very  low  cost,  where  power  is  cheap,  to  be  sold  at 
little  more  than  a  shilling  per  pound.  The  method 
whereby  a  solution  of  oxide  of  aluminium  in  fused 
cryolite  is  kept  in  the  molten  state,  and  decomposed, 
by  an  electric  current,  yields  a  metal  of  over  99  per 
cent,  purity  compared  with  the'  97  to  98  per  cent, 
metal  from  the  older  process.  The  expenditure  of 
electrical  energy  is  high,  and  in  the  light  of  our 
present  knowledge  it  appears  futile  to  endea- 
vour to  reduce  it.  When  aluminium  is  used  in 
the  thermite  process,  an  enormous  quantity  of  energy 
is  evolved  in  the  form  of  heat,  producing  a  very  high 
temperature,  the  aluminium  being  converted  into  the 
oxide.  To  win  back  the  metal  from  the  oxide  an 
equal  amount  of  energy  has  to  be  put  back,  thus 
accounting  for  the  quantity  of  energy  absorbed  in 
the  preparation  of  the  metal. 

Magnesium  was  first  isolated  by  Davy.  Ib  owes  its 
method  of  preparation  and  present-day  uses  solely  to 
scientific  investigation.  It  is  manufactured  by  a  pro- 
cess similar  to  that  used  for  aluminium,  by  the  electro- 
lysis of  fused  anhydrous  carnallite,  a  double  chloride  of 
magnesium  and  potassium.  The  "  magnalium " 
alloys  of  aluminium  and  magnesium  are  lighter  than 
the  former  metal,  give  very  good  castings,  and  are 
as  strong  as  brass  and  bronze.  The  use  of  magnesium 
in  flashlight  photography  is  well  known. 

Molybdenum  and  Tungsten,  like  aluminium  and 
magnesium,  are  children  of  science.  Both  are  used 
for  making  special  steels,  and  tungsten  is  also  formed 


TO    CHEMICAL    SCIENCE  17 

into   filaments   for  incandescent   electric   lamps,   its 
efficiency  in  this  role  being  very  great. 

Chromium,  which  was  discovered  by  Vauquelin  in 
1797,  and  is  much  used  in  the  manufacture  of  special 
steels,  has  a  very  high  melting  point,  and  on  that 
account  cannot  be  prepared  in  a  fused  state  by 
ordinary  methods.  The  metal  was  isolated  by 
Deville  by  heating  chromium  oxide  and  sugar  char- 
coal in  a  lime  crucible  ;  and  by  Wohler  by  heating 
the  chloride  with  metallic  zinc  under  a  layer  of 
sodium  chloride,  and  subsequently  removing  the 
zinc  by  treatment  with  nitric  acid,  the  chromium 
being  thereby  obtained  in  the  form  of  a  grey  powder  ; 
but  these  and  similar  methods  could  not  be  adopted 
economically  on  a  commercial  scale.  In  1893 
Moissan  published  the  method  whereby  a  mixture 
of  chromium  oxide  and  carbon  is  heated  to  the  high 
temperature  of  the  electric  furnace,  giving  a  product 
containing  large  quantities  of  carbon  from  which  it 
can  be  freed  only  by  difficult  and  expensive  processes. 
Ferrochrome,  however,  an  alloy  of  iron  containing  60 
to  70  per  cent,  of  chromium,  is  manufactured  on  a 
large  scale  by  the  thermite  process.  Chromite,  an 
ore  of  chromium  and  iron,  is  finely  crushed  and  well 
mixed  with  aluminium  dust.  The  mixture  is  ignited 
with  the  aid  of  burning  magnesium.  The  aluminium 
reduces  the  oxides  of  iron  and  chromium  with  evolu- 
tion of  great  heat,  and  consequent  production  of  a 
temperature  sufficiently  high  to  fuse  the  ferrochrome, 
the  alloy  being  thus  produced  in  a  compact  and 
homogeneous  condition.  Chromium  metal  of  over 
99 . 5  per  cent,  purity  can  be  obtained  by  the  thermite 
process,  the  principal  impurities  being  small  quanti- 
ties of  iron  and  silicon.  The  thermite  process  is  used 
when  freedom  from  carbon  is  desired,  that  of  Moissan 
being  applicable  when  the  presence  of  a  certain 
quantity  of  carbon  is  not  objectionable. 

Thorium,  discovered  by  Berzelius  in  1828,  is 
interesting  scientifically  by  reason  of  its  radioactivity. 
It  has  found  no  useful  application  as  a  metal,  but  its 
oxide,  thoria,  has  proved  invaluable  to  the  gas 
industry,  being  used  for  the  manufacture  of  incan- 


18  WHAT    INDUSTRY   OWES 

descent  mantles,  of  which  the  world's  production  is 
estimated  at  over  400,000,000  annually.  Thoria, 
when  heated  directly  in  a  flame,  possesses  the  property 
of  converting  heat  energy  into  light.  Research  was 
therefore  directed  to  the  utilisation  of  this  property, 
the  evolution  of  the  modern  gas  mantle  being  the 
result  of  purely  scientific  investigations,  requiring 
great  skill  and  patience.  Not  the  least  difficult  pro- 
blem to  be  solved  was  the  production  of  thoria  in 
the  necessary  state  of  purity.  In  the  early  history 
of  the  manufacture  of  the  mantles,  the  known  sources 
of  thoria  were  not  numerous,  although  the  available 
ores  were  rich,  and  presented  little  difficulty  in  treat- 
ment, but  the  discovery  of  large  deposits  of  monazite 
sand  in  South  America  stimulated  the  industry  by 
considerably  diminishing  the  cost  of  the  materials 
employed.  For  a  time,  while  the  value  of  the  sand 
remained  unrecognised  by  the  States  wherein  it  was 
found,  the  sand  was  shipped  to  Europe  as  ballast — an 
illustration  of  the  advantages  to  be  gained  from 
scientific  investigation  into  natural  resources.  How- 
ever, that  is  another  story  !  Monazite  is  a  complex 
mineral  consisting  of  the  phosphates  of  thorium  and 
the  metals  of  the  rare  earths,  occurring  mixed  with 
other  minerals  as  a  sand.  To  obtain  pure  thoria 
from  this  ore  a  protracted  treatment .  is  necessary, 
involving  concentration  by  tables  and  by  magnetic 
separation,  followed  by  fractional  precipitation  of 
the  oxides  from  solution.  The  thoria  appears  on  the 
market  as  nitrate.  In  the  manufacture  of  mantles 
a  cotton  framework,  supported  on  an  asbestos  collar, 
is  soaked  with  a  solution  of  the  nitrate  and  dried  ;  the 
cotton  is  burned  away,  and  the  resultant  oxide  is 
hardened  by  further  heating,  and  stiffened  by  dipping 
into  collodion,  which  in  turn  is  removed  by  burning 
when  the  mantle  is  placed  in  position  ready  for  use. 
It  was  found  that  the  presence  of  about  one  per  cent,  of 
cerium  oxide  in  the  mantle  increased  to  a  maximum 
the  transformation  of  heat  energy  into  light,  whereas 
a  marked  diminution  of  luminosity  was  observed 
when  the  quantity  of  cerium  oxide  was  increased  or 
diminished.  For  this  reason  the  equivalent  of  one 


TO    CHEMICAL    SCIENCE  19 

per  cent,  of  cerium  oxide  is  added  to  the  solution  of 
thorium  nitrate.  The  credit  for  practically  the  whole 
of  the  scientific  work  underlying  the  industry  is  due 
to  Auer  von  Welsbach. 

Vanadium,  discovered  in  1830  by  Sefstrom,  in  the 
refinery  slag  of  the  iron  ore  of  Taberg,  in  Sweden,  is 
of  increasing  service  to  the  maker  of  special  steels. 
In  effect  0 . 2  per  cent,  is  equivalent  to  3  to  4  per  cent, 
of  nickel,  and  experience  tends  to  show  that  it  imparts 
to  steel  the  power  of  resisting  changes  caused  by 
vibration,  a  most  valuable  property  from  the  engi- 
neer's point  of  view.  It  is  mainly  used  as  an  alloy, 
ferrovanadium,  prepared  by  the  thermite  process. 
It  is  worthy  of  note,  as  affording  an  instance  of  the 
utilisation  of  "  waste,"  that  the  mixture  of  metals 
obtained  by  reducing  the  rare  earth  oxides  forming 
the  residue  of  monazite  after  the  extraction  of  thoria 
is  employed,  in  the  place  of  aluminium,  to  produce 
pure  vanadium  by  a  method  resembling  the  thermite 
process. 

THE  NOBLE  METALS. 

Gold. — In  the  recovery  of  gold  large  quantities 
of  metal  were  previously  thrown  away  in  tailings, 
owing  to  the  fact  that  amalgamation  left  a  certain 
amount  unextracted  from  the  ore.  The  Plattner 
chlorine  method  and  the  Mac  Arthur -Forrest  cyanide 
process  have  now  rendered  the  tailing  metal 
available.  The  Plattner  method,  which  is  also  used 
in  the  treatment  of  auriferous  pyrites,  depends  on  the 
action  of  chlorine  gas  on  the  roasted  ore,  the  chloride 
produced  being  subsequently  leached  out  with  water. 
The  gold  is  then  precipitated  by  treating  the  solution 
with  some  suitable  material,  such  as  ferrous  sulphate, 
charcoal,  sulphuretted  hydrogen,  sulphide  of  iron,  or 
sulphide  of  copper.  The  MacArthur-Forrest  pro- 
cess, also  founded  on  the  study  of  the  chemical 
properties  of  gold,  consists  in  the  treatment  of  the 
sand  or  slime  tailings  from  the  amalgamation 
process,  or,  in  some  cases,  a  very  low  grade  ore, 
with  a  dilute  solution,  not  more  than  0.3  per  cent., 
of  potassium  or  sodium  cyanide,  and  the  subsequent 


20  WHAT    INDUSTRY    OWES 

precipitation  of  the  dissolved  gold  by  means  of  zinc 
shavings.  The  zinc  is  removed  by  distillation  from 
graphite  retorts,  or  sometimes  by  dissolution  in 
sulphuric  acid,  the  latter  method  yielding  a  somewhat 
richer  bullion.  In  a  method  introduced  by  Tavener, 
the  zinc -gold  precipitate  is  mixed  with  litharge,  saw- 
dust and  assay  slags,  and  melted  in  a  reverberatory, 
the  resultant  lead  bullion  being  subsequently  cupelled 
for  recovery  of  the  gold.  In  another  method, 
devised  by  Siemens  and  Halske,  the  gold  is  precipi- 
tated from  the  cyanide  solution  by  electrolysis,  using 
iron  anodes  and  lead  cathodes  and  recovering  the 
gold  by  cupelling  the  cathodes. 

In  the  separation  of  gold  from  silver,  nitric  acid 
was  at  one  time  universally  employed,  but  in  1802 
D'Arcet  utilised  the  fact,  discovered  in  1753  by 
Scheele,  that  concentrated  sulphuric  acid  was  equally 
suitable  for  the  purpose.  This  constituted  an  improve- 
ment of  considerable  value,  effecting  a  saving  both  of 
cost  and  time,  and  it  must  be  remembered  that  in  this 
connection  "  time  is  money,"  for  gold  brings  interest. 
The  Platinum  Group. — The  metals  of  the  plati- 
num group  are  among  the  most  valuable  acqui- 
sitions of  civilised  man,  and  their  availability  is 
entirely  due  to  chemists,  among  whom  may  be 
mentioned  Achard,  Janetty,  Knight,  Wollaston, 
Deville,  and  the  firm  of  Johnson,  Matthey  and  Co. 
Platinum  itself  is  easily  worked  by  the  oxy -hydrogen 
flame  method  of  Hare,  modified  and  improved  by 
Deville  and  Debray,  and  is  useful  for  many  purposes 
in  which  special  resistant  properties  are  essential, 
such  as  for  vessels  employed  in  analytical  chemistry, 
for  stills  for  the  concentration  of  chamber  acid, 
for  standard  weights  and  measures,  for  electrical 
leads  fused  into  glass,  as  a  catalyst  in  the  contact 
process  for  making  sulphuric  acid,  as  a  photographic 
medium,  and  for  mounting  jewellery. 

Other  members  of  the  group  are  iridium,  discovered 
by  Tennant  in  1804,  used  in  combination  with  plati- 
num in  the  construction  of  pyrometers,  and  as  pure 
metal  for  tipping  gold  pens  ;  osmium,  discovered  by 
Descotils  in  1803,  and  by  Tennant  in  1804,  used  in  the 


TO    CHEMICAL    SCIENCE  21 

preparation  of  metallic  filaments  of  electric  lamps, 
and  combined  with  iridium  for  tipping  gold  pens  and 
for  the  bearings  of  the  mariner's  compass  ;  palladium 
discovered  by  Wollaston  in  1803,  employed  by 
dentists  and  jewellers  ;  and  rhodium,  discovered  by 
Wollaston  in  1804,  used  in  the  manufacture  of  certain 
forms  of  chemical  apparatus. 

NOTE  (p.  12). — An  alloy  is  termed  eutectic  when  it  is  the 
most  fusible  of  the  alloys  of  two  metals,  the  melting 
point  being  lower  than  that  of  either  of  the  two 
metals  of  which  it  is  composed.  On  cooling  from  the 
molten  state  it  deposits  a  solid  having  the  same  com- 
position as  that  of  the  molten  mixture.  For  example, 
the  melting  points  of  lead  and  tin  are  328  and  232  deg. 
Cent,  respectively,  but  an  alloy  of  these  metals  containing 
31  per  cent,  of  lead  melts  at  180  deg.  Cent.,  any  variation 
from  this  composition  entailing  a  rise  in  the  melting  point. 
If  an  alloy  richer  in  either  constituent  be  slowly  cooled,  the 
metal  present  in  excess  of  the  above  composition  separates 
in  the  solid  state  as  cooling  progresses,  until  the  composi- 
tion of  the  remaining  fluid  is  that  of  the  eutectic,  which 
then  separates  in  the  solid  state.  In  the  case  of  alloys  of 
gold  and  silver  there  is  no  eutectic,  the  melting  points 
rising  regularly  from  that  of  silver  to  that  of  gold. 


c  2 


22  WHAT    INDUSTRY   OWES 


CHAPTER  II. 
HEAVY  CHEMICALS  AND  ALKALI. 

IN  reviewing  the  progress  made  in  chemical 
industries  proper,  we  are  met  with  such  a  condition 
of  interdependence  that  it  is  impossible  to  avoid  over- 
lapping of  the  subjects  to  be  treated.  Moreover, 
the  steps  made  in  the  improvement  and  development 
of  processes,  and  in  the  evolution  of  new  products, 
are  so  numerous  that  space  will  not  allow  of  a  com- 
prehensive scheme.  Indeed,  the  library  of  the  Patent- 
office,  one  of  the  best  for  technological  literature, 
cannot  contain  all  that  is  due  to  chemists,  nor  disclose 
to  which  chemists  the  credit  should  be  given  for  many 
important  advances.  We  must,  perforce,  recognise, 
however,  that  science  is  the  basis  of  all  substantial 
development  in  the  industrial  arts,  and  that  the  rule 
of  thumb  is  dead. 

It  has  often  been  said  that  the  prosperity  of  a 
country  might  be  gauged  by  its  output  of  sul- 
phuric acid ;  yet  it  is  remarkable  how  little 
the  man  in  the  street  realises  the  importance  of 
this  substance.  He  has  a  vague  idea  that  it  is 
the  same  thing  as,  or  in  some  way  akin  to,  vitriol, 
which  he  knows  is  destructive  to  clothing,  and  is 
associated  with  charges  of  criminal  assault  wherein 
some  evil-minded  wretch  has  employed  it  as  the 
agency  for  disfiguring  the  features  of  a  fellow-being. 
If  he  were  told  that,  even  in  normal  times,  the  world's 
output  exceeded  5,000,000  tons  he  would  marvel 
how  it  is  that  he  never  sees,  and  probably  never 
has  seen,  the  substance.  The  reason  for  this  is, 
that  the  consumer  of  large  quantities  of  the  acid 
generally  finds  it  convenient  and  economical  to  make 
it  himself.  Thus,  although  large  quantities  are 
produced  and  consumed  there  is  only  a  comparatively 


TO    CHEMICAL    SCIENCE  23 

small  quantity  on  the  market.  When  we  come 
to  consider  its  technical  applications  we  find  there 
is  scarcely  an  industry  that  does  not  depend  directly 
or  indirectly  on  its  use.  It  is  employed  in  the 
manufacture  of  superphosphate  fertiliser,  as  a  solvent 
for  metals — for  example,  in  the  parting  of  gold 
and  silver — as  a  constituent  of  dipping  baths  for 
cleansing  brass  and  bronze  castings,  and  is  used 
in  the  electrolytic  refining  of  copper.  Ammonia 
from  the  coal -tar  and  shale  oil  industries  is  absorbed 
in  sulphuric  acid,  the  resultant  sulphate  being  exten- 
sively employed  as  a  fertiliser.  (The  world's 
production  of  ammonium  sulphate  probably  exceeds 
1,500,000  tons.)  The  refining  of  oils,  fats,  and  waxes, 
and  of  tar  and  petroleum  products  is  also  carried  out 
with  the  aid  of  sulphuric  acid,  and  it  is  extensively 
used  in  the  manufacture  and  sulphonation  of  dyestuffs. 
Nitric  acid,  guncotton — and  therefore,  cordite,  collo- 
dion and  celluloid — nitroglycerine  for  dynamite, 
phenol,  picric  acid,  T.N.T.,  ether,  saccharine,  many 
drugs,  liquid  glue,  alum,  persulphates,  and  a  host 
of  other  useful  substances  are  produced  by  processes 
in  which  sulphuric  acid  is  an  essential  factor.  It 
must  be  remembered,  moreover,  that  many  such 
substances  are  but  the  starting  materials  for  the 
manufacture  of  other  products  ;  so  that  regarded 
as  a  mediaeval  ancestor,  sulphuric  acid  can  boast 
a  genealogical  tree  of  no  mean  order  with  many 
a  noble  family  and  innumerable  progeny.  Nor 
must  we  forget  that  not  the  least  important  of  its  uses 
is  in  the  laboratory,  where  also  many  of  its  relations 
are  to  be  found  among  the  reagents  required  by 
the  chemist.  Discovered  in  the  fifteenth  century 
by  the  alchemists,  it  was  made  until  about  1770 
by  two  methods  :  (i. )  by  the  distillation  of  crystallised 
sulphate  of  iron  prepared  by  roasting  iron  pyrites  ; 
and  (ii.)  by  the  combustion  of  sulphur  in  a  bell  jar 
over  water.  Of  these  methods,  the  first  survived 
until  recently,  being  the  only  method  available 
for  making  fuming  acid,  the  second  being  the  fore- 
runner of  the  modern  lead  chamber  process.  Both 
are  attributed  to  Basil  Valentine  (15th  century), 


24  WHAT    INDUSTRY    OWES 

who  next  discovered  that  by  the  addition  of  antimony 
sulphide  and  nitre,  the  yield  could  be  substantially 
increased.  Up  to  about  the  middle  of  the  eighteenth 
century  the  principal  workers  at  the  problem  had 
been  alchemists — monks  and  others — the  pioneers 
of  modern  science  ;  and  the  only  process  that  could 
be  called  a  manufacture  was  that  with  sulphate  of 
iron  as  starting  material.  At  about  that  time, 
however,  two  French  chemists,  Lefevre  and  Lemery, 
produced  a  method,  used  on  a  small  manufacturing 
scale,  wherein  a  mixture  of  sulphur  and  nitre,  without 
antimony  sulphide,  was  burned  under  a  bell-jar 
over  water.  About  1770  Dr.  Roebuck,  of  Birmingham, 
first  employed  lead  chambers  containing  water, 
instead  of  glass  bell- jars,  thus  considerably  enlarging 
the  scale  of  operations.  The  procedure  was  the  same 
as  in  the  bell-jar  method.  The  floor  of  the  lead 
chamber  was  covered  with  a  few  inches  of  water,  and 
a  kind  of  stand  in  the  middle  of  the  floor  carried  the 
charge  of  sulphur  and  nitre.  The  charge  was  ignited 
aid  the  door  was  immediately  closed  and  luted 
securely.  The  operations  of  charging,  burning,  and 
discharging  were  repeated  until  the  acid  attained 
the  maximum  strength  compatible  with  the  safety 
of  the  lead,  when  the  liquid  was  drawn  off  and  concen- 
trated. This  was  a  discontinuous  process,  but  in 
principle  it  was  the  modern  continuous  method 
in  a  primitive  state.  The  transition  from  the  one 
to  the  other  was  gradual,  the  outcome  of  much 
thought  and  research.  A  step  towards  continuity 
of  working  was  obtained  by  burning  the  sulphur 
in  a  separate  vessel,  and  leading  into  the  lead  chamber 
the  products  of  combustion,  mixed  with  excess  of 
air,  and  the  fumes  evolved  on  treating  nitre  with 
sulphuric  acid.  •  Complete  continuity  and  greater 
speed  of  working  was  obtained  when  Kestner  intro- 
duced the  injection  of  steam  into  the  chamber. 
The  rationale  of  the  process  was  explained  by  chemists 
by  the  aid  of  various  theories,  but  a  fact  of  great 
importance  was  clearly  recognised,  viz.,  that  the 
nitric  acid  was  merely  a  carrier  of  the  atmospheric 
oxygen,  and  needed  to  be  used  only  in  small  quantity. 


TO    CHEMICAL    SCIENCE  25 

Next  it  was  found  that  the  spent  gas  issuing  from 
the  chamber  gave  rise,  in  contact  with  atmospheric 
air,  to  oxidised  nitrogen  compounds  that  could  be 
used  again  in  the  chamber.  Nitre  being  the  most 
expensive  raw  material,  many  efforts  were  directed 
towards  the  recovery  of  these  gases  and  their  return 
to  the  circuit.  The  most  successful  of  these  and 
the  one  universally  adopted  was  due  to  the  great 
French  chemist,  Gay-Lussac,  the  friendly  rival 
in  many  fields  of  work  of  our  own  Sir  Humphry 
Davy.  The  gases  issuing  from  the  chamber  were 
conducted  up  a  tower  of  lead  or  stone,  packed  with 
coke,  down  which  a  slow  stream  of  strong  sulphuric 
acid  was  caused  to  trickle.  The  acid  issuing  from 
the  foot  of  the  tower  contained  all  the  oxides  of 
nitrogen  present  in  the  chamber  gas.  This  acid 
was  then  conveyed  to  the  top  of  another  tower, 
invented  by  Glover,  and  in  penetrating  the  length 
of  the  tower  was  met  by  the  hot  gases  from  the  sulphur 
burners  and  deprived  of  its  nitrogen  oxides  which 
were  returned  to  the  chamber  with  the  ingoing  gases, 
to  play  again  their  part  in  the  transformation.  The 
acid  drawn  from  the  chamber  was  concentrated 
in  glass  retorts,  platinum  being  afterwards  substituted 
for  glass.  Although  the  initial  outlay  on  platinum 
was  very  considerable,  the  loss  by  breakage  was 
avoided. 

This  short  history  of  sulphuric  acid  manufacture 
should  serve  to  illustrate  how  science  has  been  the 
primary  factor  in  its  evolution.  The  subject  of  the 
use  of  iron  pyrites  as  a  source  of  sulphur  will  be 
deferred  until  we  consider  the  alkali  industry. 

We  must  digress  for  a  moment  to  refer  to  another 
industry  in  order  to  indicate  the  origin  of  the  contact 
process.  About  thirty-six  years  ago,  various  methods 
were  discovered  for  the  preparation  of  artificial 
indigo,  and  endeavours  were  made  to  apply  the  best 
of  these  on  a  commercial  scale  to  compete  with 
the  natural  product.  The  starting  material  in  the 
most  successful  processes  was  naphthalene,  at  one 
time  regarded  by  the  tar  distiller  as  a  nuisance 
but  now  recognised  as  a  valuable  product.  In  the 


26  WHAT    INDUSTRY    OWES 

first  stage  of  the  synthesis  of  indigo,  naphthalene 
is  converted  by  oxidation  into  phthalic  acid.  This 
was  originally  effected  by  chlorination  and  subsequent 
oxidation  with  nitric  acid  ;  but  the  process  was  too 
expensive  for  successful  application  on  the  large 
scale.  Next  the  discovery  was  made  that  the  direct 
oxidation  of  naphthalene  could  easily  be  effected 
by  fuming  sulphuric  acid  in  the  presence  of  mercuric 
sulphate.  At  that  time,  however,  the  only  method 
of  preparing  the  fuming  acid  was  the  Nordhausen 
process,  by  heating  sulphate  of  iron,  and  the  product 
was  too  highly  priced  for  the  prospective  indigo 
manufacturer.  Cheap  fuming  acid  was,  therefore, 
a  necessity.  It  had  been  known  to  chemists  for 
a  half  a  century  or  more  that  sulphuric  acid  anhydride 
could  be  made  from  sulphur  dioxide  and  oxygen 
by  passing  the  mixed  gases  over  heated  finely  divided 
platinum,  and  it  was  found  that  by  absorbing  the 
anhydride  in  concentrated  sulphuric  acid  the  product 
was  the  fuming  acid.  In  the  laboratory,  where 
the  materials  employed  were  comparatively  pure, 
the  method  left  nothing  to  be  desired,  but  on  the 
works  where,  for  reasons  of  economy,  materials  of 
a  crude  nature,  such  as  pyrites,  had  to  be  used, 
further  obstacles  were  encountered.  The  process 
would  go  briskly  for  a  time  and  then  it  would  slow 
up  and  finally  stop  altogether.  The  platinum  had 
lost  its  efficiency  and  the  chemists  were  confronted 
with  another  difficulty.  They  are  accustomed  to 
this  sort  of  thing  and  enjoy  it.  Indeed,  some  are 
almost  disappointed  when  results  come  too  easily 
and  there  is  a  lull  in  the  chase.  They  found  that 
the  platinum  had  been  "  poisoned "  by  arsenic, 
antimony  and  mercury  from  the  pyrites  ;  they  there- 
fore devised  the  means  for  washing  these  oxides 
out  of  the  sulphur  dioxide,  and  with  this  purified 
material  their  labours  were  crowned  with  success. 
The  manufacture  of  fuming  acid  and  ordinary  con- 
centrated sulphuric  acid  by  the  "  contact  process  " 
is  a  fast  growing  industry,  and  will  doubtless  in 
time  largely  replace  the  lead  chamber  process  by 
reason  of  its  efficiency  and  cleanliness,  and  the 


TO    CHEMICAL    SCIENCE  27 

compactness  of  the  plant  required.  Moreover,  it 
is  convenient  and  economical  to  be  able  to  produce 
acid  of  any  strength  without  the  expense  involved 
in  the  concentration  necessary  in  the  older  process. 
On  account  of  the  diversity  of  its  uses  sulphuric 
acid  is  required  in  varying  conditions  of  purity  and 
concentration,  from  the  chamber  acid  and  B.O.V. 
of  commerce  to  the  redistilled  acid  required  in 
analytical  operations.  Researches  have  been  con- 
ducted with  a  view  to  the  elimination  of  impurities, 
and  especially  of  arsenic.  The  contact  process 
satisfies  this  requirement,  but  acid  from  the  chamber 
process  may  contain  this  impurity  in  considerable 
quantity.  The  use  of  sulphur  instead  of  pyrites 
results  in  the  production  of  arsenic  free  acid, 
but  chamber  acid  already  containing  arsenic  can 
be  freed  from  this  impurity  by  precipitating  it  as 
sulphide  with  sulphuretted  hydrogen  before  con- 
centrating the  acid.  Another  method  has  been 
suggested  whereby  dry  hydrogen  chloride  is  passed 
through  strong  sulphuric  acid  heated  above  150  deg. 
Cent.,  when  the  arsenic  is  entirely  removed  as 
trichloride,  but  this  has  not  received  extensive 
application.  Both  these  methods  are  founded  on 
everyday  laboratory  experience. 

One  hundred  and  thirty  years  ago,  as  a  result 
of  the  French  revolutionary  wars,  France  was  cut 
off  from  the  supply  of  alkali  and  an  appeal  was 
made  to  chemists  *'  to  render  vain  the  efforts 
and  hatred  of  despots,"  and,  incidentally,  to  win 
a  prize  by  producing  a  process  for  making  alkali. 
This  offer  resulted,  in  1794,  in  the  submission  to  the 
Convention  of  more  than  a  dozen  processes,  some  of 
which  had  already  been  in  operation,  including  that 
of  the  apothecary  Leblanc,  which  was  accepted.  In 
1814  it  was  introduced  into  England,  and  in  1823  the 
first  works  of  importance  were  established  near  Liver- 
pool by  James  Muspratt.  In  the  Leblanc  ^process 
sulphuric  acid  is  employed  for  the  decomposition  of 
common  salt.  The  resulting  sulphate  is  heated  with 
chalk  and  small  coal  in  a  reverberatory  furnace  ;  the 
mass  is  lixiviated  with  cold  or  tepid  water;  the 


28  WHAT    INDUSTRY    OWES 

solution  is  evaporated  to  dryness  and  the  product 
is  calcined  with  sawdust  in  a  suitable  furnace.  The 
soda-ash  or  crude  sodium  carbonate  thus  obtained 
is  dissolved  in  hot  water,  treated  with  lime,  to  obtain 
caustic  soda,  to  be  used  by  the  soap  and  candlemakers, 
or  the  solution  of  the  carbonate  in  water  is  filtered 
and  crystallised  to  give  washing  soda.  We  have 
indicated  that  the  substances  required  for  the 
process  were  salt,  coal,  chalk,  and  sulphuric  acid. 
The  first  three  were  to  be  found  in  abundance  in 
Nature,  but  up  to  that  time  sulphuric  acid  was 
comparatively  expensive,  and  the  demand  for  it 
was  not  such  as  to  warrant  its  extensive  manufacture. 
It  was  to  meet  the  requirements  of  the  Leblanc 
process  that  the  output  of  the  acid  was  enormously 
increased,  and  although  the  process  has  now  been 
superseded  by  that  of  Solvay,  as  far  as  carbonate  is 
concerned,  and  is  being  replaced  by  electrolytic 
methods  for  making  caustic  soda,  it  must  not  be  over- 
looked that  we  owe  to  Leblanc,  indirectly,  our  cheap 
sulphuric  acid,  and  therefore  a  thousand  and  one 
other  cheap  commodities. 

To  return  to  the  sodium  carbonate,  we  may  well 
ask  how  many  good  citizens  and  washerwomen 
who  use  it  have  any  idea  that  a  chemist  has  anything 
to  do  with  its  production  ?  Possibly  they  think 
it  exists  naturally  in  the  condition  supplied  ;  more 
probably  still,  they  think  nothing  at  all  about  it 
so  long  as  it  serves  its  purpose. 

If  the  crystals  are  re -dissolved  in  water,  filtered 
and  re -crystallised,  we  have  the  pure  sodium  carbonate 
used  in  pharmacy.  By  passing  carbonic  acid  gas 
into  a  cold  solution  of  the  carbonate,  and  by  placing 
the  crystals  in  an  atmosphere  of  the  gas,  we  obtain 
the  bi-carbonate  which  is  also  employed  in  pharmacy, 
and  as  an  ingredient  of  baking  powders. 

The  aim  of  the  technologist  is  to  avoid  waste 
of  any  kind,  either  of  matter  or  energy,  the  cost 
of  a  product  to  the  consumer  being  in  a  great  degree 
dependent  on  the  efficient  utilisation  both  of  raw 
material  and  of  by-products.  The  alkali  industry 
furnishes  many  examples.  In  the  Leblanc  process, 


TO    CHEMICAL    SCIENCE  29 

among  the  main  products  are  soda  ash,  which  we  have 
shown  is  purified  to  obtain  soda  crystals,  and  "  alkali 
waste,"  of  which  about  30  per  cent,  is  calcium  sulphide 
containing  the  sulphur  from  the  original  sulphuric 
acid.  The  waste  was  long  regarded  as  useless,  but  is 
now  treated  for  the  recovery  of  the  sulphur.  Many 
attempts  have  been  made  to  recover  this  sulphur  in 
a  useful  form,  but  it  was  only  comparatively  recently 
that  the  Chance-Glaus  method  was  introduced, 
whereby  the  alkali  waste  is  made  into  a  paste  with 
water,  and  acted  on  by  carbonic  acid  gas — lime -kiln 
gas  and  furnace  gas  being  used  for  the  purpose. 
The  sulphur  of  the  calcium  sulphide  is  converted 
thereby  into  sulphuretted  hydrogen,  which  is  mixed 
with  a  carefully  regulated  supply  of  air  and  burned 
in  contact  with  hot  ferric  oxide  in  Claus  kilns.  The 
hydrogen  burns  off  and  the  sulphur  is  deposited 
in  a  practically  pure  state — a  very  valuable  product. 
When,  in  1839,  an  export  embargo  was  placed 
on  Sicilian  sulphur,  the  alkali  manufacturers,  having 
to  look  elsewhere  for  their  supply,  found  it  in  iron 
pyrites.  The  residue  of  oxide  of  iron  from  the  pyrites 
burners  was  not  used  as  a  source  of  iron,  as  it  retained 
enough  sulphur  to  render  it  unfit  for  this  purpose. 
The  pyrites  used  also  contained  a  certain  amount 
of  copper,  averaging  3  per  cent.,  as  well  as  small 
quantities  of  gold  and  silver.  Until  1865  these 
residues  were  dumped  as  useless,  but  in  that  year 
Henderson  introduced  a  method  whereby  the  whole 
of  the  copper  could  be  recovered  by  roasting  the 
residues  with  common  salt,  lixiviating  the  mass 
with  water,  and  precipitating  the  copper  from  the 
resultant  solution  by  means  of  scrap  iron.  In  1870, 
a  method  was  devised  by  Claudet  to  recover  the  gold 
and  silver  occurring  in  the  residues.  The  copper 
solution  formed  on  lixiviation  in  Henderson's  process 
contains  the  gold  and  silver  as  chlorides  dissolved 
in  the  excess  of  common  salt.  By  Claudet' s  method 
the  gold  and  silver  are  precipitated  by  the  addition 
of  zinc  iodide  to  this  solution,  the  precipitated 
iodides  being  subsequently  reduced  with  metallic 
zinc  in  the  presence  of  hydrochloric  acid. 


30  WHAT    INDUSTRY    OWES 

Thus  by  the  application  of  science  the  revenue 
of  the  sulphuric  acid  and  alkali  maker  increased, 
the  price  of  his  products  is  lowered,  and  valuable 
materials  are  rescued  from  the  dump.  More 
than  500,000  tons  of  pyrites  are  burned  annually 
in  England  for  the  sake  of  the  sulphur.  The  residue 
from  this  yields  on  extraction  about  15,000  tons  of 
copper,  400,000  ounces  of  silver,  and  2000  ounces 
of  gold,  the  final  residue  being  transformed  into  a 
valuable  source  of  iron. 

In  connection  with  this  subject  can  be  related  one 
of  the  most  interesting  episodes  in  indurstrial  history. 
For  some  time  after  the  inception  of  the  Leblanc 
process,  the  hydrochloric  acid  produced  was  allowed 
to  escape  into  the  air,  as  no  use  had  been  found  for 
it.  Metal  ware  was  corroded,  and  vegetable  growth 
destroyed  for  miles  around  the  works  and  the  nuisance 
gave  rise  to  much  litigation.  The  obvious  remedy 
was  to  absorb  the  noxious  gas,  and  to  effect  this 
many  of  the  larger  works  adopted  in  1836  a  method 
devised  by  Gossage.  It  was  not  until  1863,  however, 
that  the  Alkali  Act  was  passed,  enacting  that  not 
less  than  95  per  cent,  of  the  hydrochloric  acid  gas 
produced  should  be  absorbed,  a  regulation  rendered 
more  stringent  by  subsequent  legislation.  Some  idea 
of  the  quantity  concerned  may  be  gathered  from  the 
fact  that  at  that  time  about  3000  tons  of  the  gas 
were  produced  annually  in  England.  To  hark 
back  to  the  earlier  days  when  the  makers  first  laid 
out  capital  to  provide  means  for  the  absorption 
of  the  gas,  they  naturally  wondered  what  return 
they  could  get  for  it.  This  was  forthcoming  in  the 
increased  demand  for  chlorine  to  make  bleaching 
powder  to  be  used  for  bleaching  raw  cotton  and 
materials  for  paper  making.  Chlorine,  set  free  from 
the  hydrochloric  acid  by  the  action  of  manganese 
dioxide,  was  led  over  slaked  lime,  and  the  product 
was  bleaching  powder.  The  same  gas  passed  into 
cold  solutions  of  caustic  soda  and  potash  formed 
useful  bleaching  solutions,  while  if  boiling  potash  was 
used  the  product  was  chlorate  of  potash,  a  valuable 
substance  in  pyrotechny,  in  the  manufacture  of 


TO    CHEMICAL    SCIENCE  31 

certain  explosives,  and  in  medicine.  The  manganese 
dioxide  employed  to  liberate  the  chlorine  was 
converted  into  a  useless  product,  which  was  a  loss 
to  the  manufacturer.  Science  again  came  to  his 
aid  in  the  discovery  of  Weldon,  that  the  action  of 
lime  and  air  on  the  manganese  waste  resulted  in 
the  regeneration  of  an  oxygenated  body  which  might 
be  used  in  exactly  the  same  way  as  the  original 
dioxide.  Thus,  by  this  process  the  dioxide  acts 
merely  as  an  agent  in  liberating  the  chlorine,  and 
can  be  used  over  and  over  again,  atmospheric  oxygen 
being  the  real  factor  concerned  in  the  change. 

The  Deacon  process  for  the  manufacture  of  chlorine 
from  hydrochloric  acid  is  a  scientific  method,  whereby 
hydrochloric  acid  gas  and  air  are  passed  over  hot 
brick-work  impregnated  with  copper  salts.  The 
products  are  chlorine  gas  and  water,  the  copper 
salts  acting  merely  as  carriers  of  oxygen.  The  only 
losses  are  that  of  the  hydrogen  of  the  hydrochloric 
acid  and  the  oxygen  of  the  air. 

The  two  processes  last  considered,  together  with 
the  lead  chamber  sulphuric  acid  process,  being  among 
the  earliest  of  this  type  to  be  employed,  serve  to 
show  how  the  chemist  is  teaching  the  manufacturer 
to  use  catalytic*  and  contact  agents  to  effect  certain 
chemical  changes — more  especially  those  involving 
oxidation.  Such  processes  are  numerous  and  success- 
ful at  the  present  day,  effecting  wonderful  economies, 
needing  only  simple  and  compact  plant,  and  bringing 
about  the  required  changes  in  the  cleanest  and  least 
wasteful  manner. 

The  Ammonia-Soda  or  Solvay  Process. — In  this 
process  sodium  bicarbonate  is  produced  by  the  action 
of  carbon  dioxide  on  an  ammoniacal  solution  of 
common  salt.  The  bicarbonate  crystallises  out, 
leaving  ammonium  chloride  in  solution,  the  ammonia 
being  recovered  by  heating  the  solution  with  lime, 
and  used  over  again.  The  lime  employed  is  burnt  at 
the  works,  the  lime-kiln  gas  being  the  source  of  some 
of  the  carbon  dioxide,  while  the  gas  expelled  from 
the  bicarbonate  by  calcination  to  make  normal 
carbonate  provides  the  remainder.  The  salt  solution 


32  WHAT    INDUSTRY    OWES 

used — brine  pumped  up  from  brine  pits — is  subjected 
to  preliminary  purification.  Magnesium  salts  are 
precipitated  by  the  addition  of  lime,  the  lime  salts 
being  afterwards  removed  by  adding  the  necessary 
quantity  of  sodium  carbonate  or  ammonia  liquor 
containing  ammonium  carbonate.  After  settling  the 
solution  is  drawn  off  and  is  then  ready  for  use. 

This  process,  which  was  patented  by  Dyer  and 
Hemming  in  1838,  though  simple  from  the  chemists' 
point  of  view,  presented  considerable  mechanical 
difficulties.  The  first  attempt  to  utilise  the  reaction 
on  the  large  scale  was  made  by  Schloessing  and 
Holland  in  1855,  at  a  works  near  Paris.  At  the  end 
of  two  years,  however,  the  difficulties  remained 
unsolved  and  the  project  was  abandoned.  In  1863, 
Solvay,  who  had  taken  out  a  patent  two  years  earlier, 
erected  an  experimental  factory  near  Brussels  ;  as  the 
result  of  perseverance,  he  secured  the  success  of  the 
process,  and  in  1872  established  a  far  larger  works 
near  Nancy.  Two  years  later  the  process  was  intro- 
duced into  this  country,  under  the  Solvay  patents,  by 
Mond,  continued  by  Brunner,  Mond  and  Co.,  Limited, 
at  Northwich,  where  for  the  first  time  natural  brine 
was  employed  and  other  improvements  were  adopted. 
In  1895  the  production  by  the  Solvay  process  exceeded 
that  by  the  Leblanc  process,  over  which  it  has  several 
incontestable  advantages.  The  use  of  brine  from  the 
pits  effected  a  great  economy  that  could  not  be 
shared  by  the  older  process.  The  Solvay  process  is 
cleaner  and  the  product  purer.  There  is,  of  course, 
no  sulphur  to  be  recovered,  but  the  chlorine  from  the 
salt  is  frequently  wasted  as  calcium  chloride.  As  an 
improvement  in  the  process,  magnesia  is  now  used  in 
some  cases  to  liberate  the  ammonia  from  the  mother 
liquor,  the  resulting  magnesium  chloride  being 
subsequently  decomposed  by  heat  into  magnesia  (to 
be  used  over  again)  and  hydrochloric  acid. 

Before  leaving  the  subject  of  alkali  we  must  note 
that  electrolytic  methods  of  manufacture  form  an 
increasingly  important  branch  of  the  industry. 
Solutions  of  common  salt  are  electrolysed  in  a  special 
vessel,  of  which  the  Castner  rocking  cell  is  a  type, 


TO    CHEMICAL    SCIENCE  33 

and  caustic  soda  and  chlorine,  both  marketable 
products,  are  obtained  in  separate  compartments. 
When  the  process  is  modified  so  that  the  chlorine 
is  allowed  to  come  into  contact  with  the  soda  solution, 
chlorate  or  hypochlorite  may  be  produced  by 
employing  hot  or  cold  solutions  respectively.  The 
value  of  chlorates  has  already  been  indicated ; 
sodium  hypochlorite  is  used  as  a  bleaching  agent  and 
as  an  ingredient  in  one  step  of  the  manufacture 
of  indigo. 


34  WHAT    INDUSTRY    OWES 


CHAPTER  III. 
COAL  AND  COAL  GAS. 

WE  live  in  an  age  of  coal  and  iron.  The  great  war 
is  waged  very  much  with  coal — or  rather,  what  we 
get  from  it — and  iron  ;  on  the  manipulation  of  these 
substances  by  engineers  and  chemists  the  produc- 
tion of  munitions  of  war  largely  depends.  Some  of 
the  coal  we  use  to  smelt  the  iron  ore  and  to  fashion 
the  metal  into  convenient  form  for  our  use.  When 
we  have  won  the  iron  we  can  use  it,  scrap  it,  and  use 
it  again  many  times,  but  the  coal  once  used  is 
destroyed  for  all  time.  The  world's  annual  production 
of  this  valuable  mineral  probably  exceeds  1 ,335,000,000 
short  tons,  and  it  is  utilised  (1)  as  a  domestic  fuel, 
with  which  we  are  all  familiar  ;  (2)  as  a  source  of 
mechanical  and  electrical  power  through  the  agency 
of  steam  ; .  (3)  as  a  reducing  agent  in  certain  chemical 
and  metallurgical  operations  ;  (4)  for  the  production 
of  coke  in  ovens  ;  (5)  as  a  source  of  gas  for  illumi- 
nating and  heating  purposes  and  of  many  other 
valuable  products. 

The  influence  of  scientific  thought  on  the  second  of 
these  uses  is  well  known,  though  perhaps  its  extent 
is  not  always  clearly  recognised.  For  more  than 
half-a-century,  steam  engines  were  designed  to  meet 
the  requirements  of  coal  as  a  fuel.  It  was  the  bed- 
rock of  the  art  of  engineering.  The  abundance  of 
coal  gave  impetus  to  invention  and  the  modern  steam 
engine  is  the  result  of  the  co-operation  of  physicists, 
chemists  and  mathematicians,  with  the  practical  engi- 
neer. As  a  reducing  agent  in  applied  chemistry  and 
metallurgy  coal  itself  is  less  used  than  coke.  The 
ironmaster  is  a  great  consumer  of  coke-oven  coke  as 
a  reducing  agent,  and  it  has  found  an  important  use 
in  the  manufacture  of  water  gas  and  producer  gas. 


TO    CHEMICAL    SCIENCE  35 

The  first,  a  mixture  rich  in  hydrogen  and  carbon 
monoxide,  is  obtained  by  passing  steam  through  red 
hot  coke  ;  the  second,  a  mixture  of  carbon  monoxide 
and  atmospheric  nitrogen  is  formed  by  the  similar 
treatment  of  carbon  dioxide  produced  by  the  com- 
bustion of  coke.  Although  water  gas  has  a  much 
greater  calorific  power  than  producer  gas,  it  is  not 
economical  to  make  it  alone,  because  the  reaction 
between  the  coke  and  the  steam  is  endothermic  and 
the  coke  chamber  must  be  heated  externally  to  main- 
tain the  requisite  temperature.  Dowson  gas  and 
Mond  gas  are  mixtures  intermediate  between  water 
gas  and  producer  gas,  made  by  combining  the  two 
processes  and  passing  a  mixture  of  steam  and  air  over 
the  red  hot  coke.  When  the  coke  cools  during  the 
operation  the  temperature  is  raised  again  by  cutting 
off  the  steam  and  allowing  air  alone  to  pass  through. 
The  use  of  these  gases  for  heating  purposes  is  very 
economical  and  finds  extensive  application. 

As  one  of  the  most  striking  examples  of  the  influence 
of  science  in  industry,  coal  gas  manufacture  demands 
consideration  in  somewhat  fuller  detail,  treating  of 
the  distillation  of  a  highly  complex  body  from  which 
the  chemist  has  obtained  a  vast  variety  of  useful 
substances.  The  history  is  interesting  also  as  an 
illustration  of  a  development  of  philosophical  experi- 
ment. In  the  seventeenth  century  the  pursuit  of 
science  was  the  hobby  of  many  men  of  learning  and 
particularly  of  the  clergy.  The  Rev.  Dr.  Clayton, 
rector  of  Crofton,  distilled  gas  from  coal  and  collected 
it  in  a  bladder  ;  the  fact  being  communicated,  in 
1688,  to  the  Royal  Society  by  Boyle.  In  1750,  Dr. 
Watson,  Bishop  of  Llandaff,  not  only  distilled  gas 
but  conveyed  it  in  pipes  from  one  place  to  another. 
The  credit,  however,  is  given  to  an  engineer,  William 
Murdock,  for  the  first  suggestion  that  coal  gas  should 
be  generally  employed  for  lighting  purposes.  In 
1792  he  conveyed  it  from  iron  retorts  through  tinned 
iron  and  copper  pipes,  tapped  at  intervals,  a  distance 
of  70ft.,  lighting  his  house  and  offices.  His  early 
experiments  were  carried  out  at  Redruth,  and  six 
years  later  he  lighted  the  Soho  foundry  of  Boulton  and 


36  WHAT    INDUSTRY    OWES 

Watt,  at  Birmingham.  In  1799,  Le  Bon  commenced 
similar  experiments  in  France.  In  1807,  after  one 
side  of  Pall  Mall  had  been  lighted  by  Winsor,  a  Bill 
was  promoted  in  Parliament  to  authorise  a  company 
for  the  supply  of  gas  in  London  ;  in  1810  an  Act  was 
passed  for  this  purpose,  and  two  years  later  a  charter  of 
incorporation  was  granted  to  the  Gas  Light  and  Coke 
Company,  still  by  far  the  largest  gas  undertaking  in 
the  world.  Westminster  Bridge  and  the  Houses  of 
Parliament  were  lighted  in  1813,  and  from  that  time 
the  practice  of  gas  lighting  spread  rapidly  in  all 
civilised  countries. 

The  gas  industry  is  essentially  chemical,  though  it 
was  formerly  entirely  controlled  by  engineers.  There 
was  a  time  when  gas  engineers  were  disinclined  to 
show  much  appreciation  of  the  chemical  aspects  of 
the  industry.  In  some  works  the  chemists,  if  any 
were  employed,  were  exclusively  relegated  to  the 
laboratory  for  routine  testing  without  any  opportunity 
of  acquiring  experience  in  large  scale  operations.  The 
remuneration  and  prospects  of  such  chemists  were  so 
poor  that  few  worthy  of  the  name  could  be  induced 
to  remain  long  in  such  employment.  In  many 
important  works,  however,  chemists  acquired  the 
essential  knowledge  of  the  engineering  side  of  the 
industry,  led  the  way  in  the  introduction  of  improved 
methods  and  effected  developments  of  a  far-reaching 
character,  especially  in  the  profitable  utilisation  of 
material  hitherto  regarded  as  waste  and  the  manu- 
facture of  new  products. 

Enormous  quantities  of  coal  are  subjected  to 
destructive  distillation  to  obtain  its  numerous  and 
valuable  decomposition  products,  of  which  gas,  tar, 
ammonia  and  its  salts,  coke,  and  gas  carbon  are  made 
on  a  huge  scale  and  all  consumed.  The  gas  provides 
light  and  heat,  whilst  the  tar,  useful  in  many  ways  in 
the  crude  state,  gives,  when  distilled,  benzene,  toluene, 
solvent  naphtha,  carbolic  acids,  naphathalene,  anthra- 
cene, and  many  other  substances,  which  in  their  turn 
yield,  in  the  hands  of  the  technologist,  a  host  of  further 
useful  bodies,  including  explosives,  dyes,  disinfectants, 
and  drugs.  Pitch,  the  residue  of  tar  distillation,  is 


TO    CHEMICAL    SCIENCE  37 

used  largely  in  the  manufacture  of  patent  fuel  and 
provides  excellent  material  in  road  making.  Ammo- 
nia is  employed  in  medicine,  in  the  laboratory,  and  in 
cleaning  cloth,  and  there  are  many  uses  for  its  salts, 
especially  the  sulphate,  a  valuable  fertiliser.  Gas 
carbon,  a  hard,  compact  substance,  is  used  by  electrical 
engineers  in  the  operation  of  arc  lamps  and  fur- 
naces, and  as  a  fuel  in  making  producer  gas. 

The  purified  coal-gas  of  commerce  roughly  consists 
of — hydrogen  about  50  per  cent,  by  volume,  and 
marsh  gas  or  carburetted  hydrogen  about  35  per  cent., 
carbon  monoxide  5  per  cent.,  heavy  hydrocarbons 
5  per  cent.,  and  nitrogen  5  per  cent.  As  it  issues 
from  the  hydraulic  mains,  which  receive  the  vapour 
from  the  ascension  pipes  from  the  retorts,  it  is  not 
at  once  ready  for  delivery  to  the  consumer.  Besides 
its  essential  constituents,  it  contains  substances 
such  as  condensable  hydrocarbons,  ammonia,  carbon 
dioxide,  carbon  bisulphide,  sulphuretted  hydrogen, 
cyanogen,  and  cyanides,  some  of  which  are  of  sufficient 
value  to  pay  for  their  extraction,  all  being  undesirable 
impurities  on  account  of  their  reducing  the  heating 
power  of  the  gas  or  of  the  objectionable  character 
of  the  products  of  their  combustion.  These  bodies 
are  therefore  removed  by  condensation  by  cooling, 
"  scrubbing  "  with  water,  and  by  passing  the  gas 
over  suitable  materials.  The  operation  of  scrubbing 
with  water  or  with  aqueous  liquors  from  the  hydraulic 
mains  removes  the  ammonia  and  part  of  the  carbon 
dioxide.  The  gas  then  passes  into  a  chamber 
containing  moist  slaked  lime,  where  cyanogen  com- 
pounds and  the  remainder  of  the  carbon  dioxide 
are  removed,  the  former  in  a  state  from  which  they 
cannot  be  recovered.  Their  recovery  from  the  gas, 
however,  can  be  effected,  when  desired,  by  a  pre- 
liminary treatment  with  oxide  of  iron  before  the 
gas  passes  through  the  lime  chambers. 

After  the  lime  treatment  the  gas  is  led  over  moist 
oxide  of  iron,  or  Weldon  mud,  for  absorption  of 
the  sulphuretted  hydrogen,  the  material  when 
spent  being  revivified  by  action  of  the  air.  The 
gas  next  passes  over  sulphided  lime — the  substance 

D  2 


38  WHAT    INDUSTRY    OWES 

formed  by  the  action  of  sulphuretted  hydrogen  on 
slaked  lime — to  eliminate  carbon  bisulphide,  and, 
finally,  undergoes  an  extra  check  treatment  with 
oxide  of  iron,  or  Weldon  mud,  to  remove  any  traces 
of  sulphuretted  hydrogen  taken  up  from  the  sulphided 
lime.  Subject  to  passing  the  prescribed  tests  for 
illuminating  and  heating  power,  the  gas  now  passes 
to  the  holder — in  ordinary  parlance  the  gasometer — 
and  is  ready  for  the  public  supply. 

It  is  obvious  that  science  is  responsible  for  such 
a  process  of  purification.  There  is  scope  for  chemistry, 
physics,  and  mechanics  in  every  step. 

We  have  stated  that  the  pipes  from  the  retorts 
convey  the  vapour  to  the  hydraulic  main,  where  it 
is  partially  condensed,  and  the  liquid  thus  condensing 
forms  two  layers,  coal  tar  and  aqueous  liquor.  The 
latter  is  uppermost,  and  contains  ammonia  and  other 
soluble  bodies.  The  tar  was  for  long  the  bugbear 
of  gas  manufacture,  its  disposal  being  a  difficult 
problem,  but  now  it  is  of  such  value  that  the  industry 
of  tar  distillation  has  grown  to  be  of  great  importance. 
It  is  distilled  in  large  iron  stills,  the  vapours  evolved 
from  which  are  condensed,  the  distillate  being 
separated  into  fractions  as  follows  : — First  runnings 
up  to  105  deg.  Cent.  ;  light  oil  from  105  to  210  deg. 
Cent. ;  carbolic  oil  from  210  to  240  deg.  Cent. ;  creosote 
oil  from  240  to  270  deg.  Cent. ;  anthracene  oil  from 
270  up  to  the  pitching  point,  this  last  temperature 
being  determined  by  the  quality  of  pitch  desired. 
The  first  runnings  form  two  layers  in  the  receiver, 
consisting  of  ammoniacal  liquor  and  crude  naphtha. 
These  are  separated,  the  former  being  added  to  the 
bulk  of  ammoniacal  liquor,  the  latter  being  reserved 
for  subsequent  treatment.  The  second  or  light  oil 
fraction,  consisting  mainly  of  hydrocarbons  of  the 
benzene  series,  is  first  re-distilled,  yielding  first 
runnings,  which  are  added  to  the  crude  naphtha 
from  the  original  tar  first  runnings,  and  last  runnings 
which  are  worked  up  with  the  carbolic  oil. 

The  crude  naphtha  is  washed  with  caustic  soda 
solution  to  remove  phenols  in  an  easily  recoverable 
fonn  ;  then  with  strong  sulphuric  acid,  which  dis- 


TO    CHEMICAL    SCIENCE  39 

solves  bases  and  unsaturated  bodies,  and  carbonises 
other  impurities,  forming  substances  of  a  heavy, 
tarry  nature,  and  finally  another  soda  washing  is 
given  to  remove  the  residual  sulphuric  acid.  The 
spent  sulphuric  acid  Is  used  in  the  ammonia  plant 
for  the  production  of  sulphate  of  ammonia.  The 
naphtha  so  far  purified  is  next  redistilled  from  an 
iron  still.  Two  fractions  are  collected — crude  benzol 
up  to  140  deg.  Cent.,  and  solvent  naphtha  from  140 
to  170  deg.  Cent.,  the  residue  in  the  still  being  reserved 
for  addition  to  the  carbolic  oil.  From  the  crude 
benzol  are  obtained  by  further  acid  and  alkali  washing 
and  careful  fractionation,  forerunnings  of  benzol, 
containing  benzene,  toluene,  carbon  bisulphide  and 
thiophenes,  commercial  and  pure  benzol  and  toluol, 
and  solvent  naphtha.  Benzols  and  toluols  are  used 
by  the  dye  manufacturers,  and  at  the  present  day  in 
enormous  quantities  in  the  manufacture  of  explosives, 
benzene  being  the  starting  point  in  one  process 
for  making  picric  acid,  toluene  being  the  material 
from  which  T.N.T.  is  made.  Solvent  naphtha  is 
used  as  a  solvent  for  india-rubber,  the  higher  boiling 
portions  containing  naphthalene,  forming  a  fuel  for 
naphtha  lamps. 

The  carbolic  oil  is  treated  by  cooling  to  separate 
naphthalene,  and  subsequently  washing  with  a 
solution  of  caustic  soda,  which  dissolves  the  carbolic 
and  cresylic  acids.  These  acids  are  recovered  by 
neutralising  the  solution  with  sulphuric  acid,  when 
crude  carbolic  acid  and  sodium  sulphate  are  formed, 
the  former  being  subsequently  worked  up  for  pure 
carbolic  acid  and  cresylic  acid,  both  used  in  the 
manufacture  of  dyes,  disinfectants,  and  explosives. 
A  modification  of  the  above  method  is  that  known  as 
the  West-Knight  and  Gall  process,  whereby  the 
oil  is  treated  with  a  mixture  of  sodium  sulphate 
solution  and  lime  for  the  production  of  sodium 
"  carbolate "  and  sulphate  of  lime.  The  solution 
is  worked  up  as  before,  the  sodium  sulphate  being 
utilised  again  for  mixing  with  more  lime.  The 
insoluble  oil  is  either  mixed  with  the  light  oil  or  is 
worked  up  for  naphthalene. 


40  WHAT    INDUSTRY    OWES 

Creosote  oil  is  of  value  as  a  source  of  naphthalene, 
and  for  preserving  wood  from  the  action  of  the 
weather  and  destructive  insects.  Naphthalene,  once 
a  waste  product,  is  now  used  largely  in  the  manufac- 
ture of  dyes,  being  the  parent  substance  of  artificial 
indigo,  as  an  insecticide,  and  in  other  minor  roles. 
Anthracene  oil  is  the  source  of  anthracene,  a  condensed 
hydrocarbon  of  the  benzene  series,  from  which  the 
alizarin  dyes  are  made. 


TO    CHEMICAL    SCIENCE  41 


CHAPTER  IV. 
DYES,  EXPLOSIVES  AND  CELLULOSE. 

THE  invention  of  dyeing  has  been  attributed  to  the 
Phoenicians,  probably  because  it  is  chronicled  that 
Solomon  sent  to  Hiram  of  Tyre  for  "  a  man  cunning 
to  work  "  inter  alia  "  in  purple  and  crimson  and  blue." 
The  Tyrian  purple  was  derived  from  the  throats  of  a 
species  of  murex,  a  molluscous  animal,  a  single  drop 
from  each.  Other  dyes  from  animal  substances 
include  sepia  derived  from  the  black  secretion  of  the 
cuttlefish,  and  cochineal  which  consists  of  dried  female 
cochineal  insects,  discovered  by  the  Spaniards  in 
1518. 

The  importance  of  the  dye  industry  is  not  so  much 
in  the  value  of  the  dyes  as  in  the  vast  interests  of  the 
textile  industry  with  which  it  is  so  intimately 
associated.  At  a  high  estimate  this  country  does  not 
use  annually  dyes  to  the  value  of  £2,000,000,  or,  say, 
less  than  Is.  per  head,  presuming  the  use  to  be 
confined  to  the  British  Isles  ;  but  the  various  industries 
affected  exceed  in  annual  value  a  sum  of  £200,000,000, 
and  the  labour  involved  in  dyeing  and  printing 
processes  is  not  far  short  of  2,000,000.  Clearly  then 
we  cannot  afford  to  be  dependent  on  other  countries 
for  supplies  of  materials  of  this  kind  so  long  as  we  have 
the  power  to  produce  them  ourselves.  It  is  well 
known  that  the  Government  has  now  given  active  sup- 
port to  the  industry  ;  and  we  may  rejoice  that  British 
Dyes,  Limited,  and  other  British  dye  concerns  are 
making  good  progress  towards  its  firmer  establishment. 
Even  before  the  outbreak  of  war,  progress  had  been 
made  in  certain  directions  towards  successful  com- 
petition with  the  Germans,  and  since  the  war,  by  the 
aid  of  science,  discoveries  have  been  made  which,  in 
the  view  of  the  enemy  producers,  were  calculated  to 


42  WHAT    INDUSTRY   OWES 

defy  our  chemists  for  at  least  ten  years.  Compared 
with  the  period  occupied  by  the  Germans  in  dis- 
covering artificial  indigo — about  thirty-five  years  and 
an  expenditure  of  over  £1,000,000 — the  taunt  may  be 
taken  as  a  compliment ;  but  in  two  years  from  the 
discovery  of  artificial  indigo  426,100  out  of  755,900 
acres  of  plantations  went  out  of  cultivation.  It  was 
first  sold  in  1897  and  in  the  course  of  a  few  years  drove 
the  natural  dyestuff  out  of  the  markets  of  the  world, 
being  only  about  one-third  of  the  price,  and  the  busi- 
ness passed  from  India  to  Germany. 

The  history  of  the  subject  covering  the  consideration 
of  all  the  dyes  known  would  fill  volumes  exceeding  in 
bulk  the  "  Encyclopaedia  Britannica."  The  number  of 
dyes  revealed  by  science  and  the  substances  which 
science  can  foretell  with  certainty  would  form  dyes, 
and  the  myriad  derivatives  of  known  colouring 
matters,  would  run  into  many  thousands,  though 
800  to  1000  should  be  more  than  sufficient  for  all 
practical  purposes. 

The  artificial  dyes  have  several  advantages  over 
natural  products.  The  range  of  shade  for  any  colour 
can  be  extended  and  graded  by  the  employment  of 
suitable  materials  in  a  manner  that  cannot  be  attained 
by  using  the  natural  dyes  ;  the  purity  of  artificial 
dyes  is  much  greater,  and  the  total  cost  of  production  is 
considerably  less.  On  account  of  this  superiority  of 
synthetic  dyes,  the  cultivation  of  indigo  and  madder, 
and  the  trade  in  cochineal  have  been  almost  completely 
overshadowed.  Both  indigo  and  madder  have  been 
investigated  by  scientific  men,  and  the  composition 
and  nature  of  the  dyestuffs  determined.  Further 
researches  have  led  to  the  discovery  of  methods  of 
synthesis  of  these  substances,  not  only  interesting 
from  an  academic  point  of  view,  but  capable  of  holding 
their  own  and  beating  their  natural  prototypes  in 
commercial  competition.  The  use  of  cochineal  has 
been  largely  replaced  by  the  discovery  and  utilisation 
of  azo-red  dyes  which  imitate  the  colour  very  closely, 
such,  for  example,  as  Bieberich  scarlet.  The  most 
important  material  used  in  the  economical  manu- 
facture of  indigo  is  naphthalene  obtained  from  the 


TO    CHEMICAL    SCIENCE  43 

creosote  oil  fraction  of  the  tar  distiller  by  cooling, 
washing  the  crystals  produced  with  alkali  and  with 
acid,  and  distilling  or  subliming  the  product.  Other 
ingredients  are  chloracetic  acid  and  sodium  hypo- 
chlorite,  the  preparation  of  which  provides  one  of  the 
numerous  outlets  for  the  elementary  chlorine  of  the 
alkali  manufacturer.  A  short  sketch  of  the  method 
of  Heumann  will  not  be  out  of  place. 

Naphthalene  is  converted  into  phthalic  anhydride 
by  heating  with  sulphuric  acid  and  mercuric  sulphate. 
The  phthalic  anhydride  in  turn  is  transformed  into 
phthalimide  by  heating  under  pressure  with  ammonia. 
By  the  action  of  sodium  hypochlorite  on  phthalimide, 
anthranilic  acid  is  produced  and  this  substance,  when 
treated  with  chloracetic  acid,  yields  phenyl  glycine- 
carboxylic  acid,  which  by  fusing  with  alkali,  dissolving 
the  melt  in  water  and  passing  a  stream  of  air  through 
the  solution,  yields  indigo  blue.  This  complex  series  of 
operations  has  met  with  complete  commercial  success. 

Alizarin,  the  dyestuff  contained  in  madder,  is  made 
from  anthracene,  another  coal  tar  product,  by  the 
action  of  sodium  bichromate  and  sulphuric  acid  to 
form  anthraquinone  ;  this  is  transformed  by  the  action 
of  sulphuric  acid  into  anthraquinone  sulphonic  acid, 
the  sodium  salt  of  which  when  fused  with  soda  and 
a  little  potassium  chlorate  yields  a  compound  of 
alizarin  containing  sodium,  from  which  alizarin  itself 
is  made  by  the  action  of  acid. 

Bieberich  scarlet,  one  of  the  naphthol  azo  dyes, 
a  very  important  group,  is,  like  indigo,  prepared  from 
naphthalene  as  starting  material. 

These  three  examples  serve  to  show  how  the 
laboratory  and  the  factory  have  replaced  the  cultiva- 
tion field.  There  are  also  thousands  of  new  dyes 
prepared  from  benzene,  toluene,  and  carbolic  acid,  as 
well  as  many  others  from  naphthalene.  The  name 
"  coal  tar  dyes,"  however,  is  rather  misleading  to  the 
uninitiated,  for  it  seems  to  imply  that  the  dyes  exist  as 
such  in  the  tar  and  only  need  extraction.  What  is 
meant,  is  that  the  raw  materials  are  found  in  the  tar 
and  need  to  be  transformed  before  anything  of  the 
nature  of  a  dye  can  be  produced. 


44  WHAT   INDUSTRY    OWES 

The  recovery  and  utilisation  of  these  tar  products 
in  the  manner  indicated  is  a  great  achievement.  The 
first  known  coal  tar  colour  mauveine  was  made  from 
aniline  by  Perkin  in  1856,  aniline  having  been 
discovered  by  Unverdorben,  thirty  years  earlier,  by 
distilling  indigo. 

Dyeing. — The  processes  of  dyeing  and  calico 
printing  are  definitely  chemical  and  depend  entirely 
on  scientific  control.  Dyes  are  transparent  and  the 
effects  they  produce  vary  according  to  the  light 
reflected  by  the  fibres  of  materials  before  they  are 
dyed.  Obviously,  therefore,  black  cannot  be  dyed, 
and  such  colours  as  red,  blue,  and  yellow  can  only 
be  dyed  in  the  same  hues,  unless  the  material,  as  is 
possible  in  the  case  of  velvets  and  velveteens,  be 
previously  bleached.  White  reflects  all  rays  and 
is  essential  as  the  basis  for  bright  dyes.  There  must 
be  chemical  combination  between  the  colouring 
matter  and  the  cloth,  and  the  dye  must  be  dissolved 
in  a  solution  having  a  weaker  affinity  for  the  colour 
than  the  cloth,  while  for  economical  working  there 
must  be  accurate  adjustment  between  these  relations. 
Wool  has  a  stronger  affinity  for  dyes  than  silk,  cotton, 
or  linen.  The  solutions  used  must  be  varied  as 
occasion  requires.  The  choice  of  dyes  for  a  given 
material  involves  the  consideration  of  fastness  to 
washing,  and  the  action  of  light.  Certain  dyes  will 
fix  themselves  directly  to  certain  fibres  but  not  to 
others  without  the  use  of  mordants.  The  mordants 
commonly  employed,  such  as  tannin,  and  the  oxides  of 
iron  and  aluminium,  were  discovered  empirically, 
but  science  has  explained  their  action,  while  research 
has  contributed  to  the  discovery  of  many  new  kinds 
of  colouring  matter.  In  the  art  of  dyeing  the  neglect 
of  science  is  mainly  responsible  for  the  loss  incurred 
by  spoiled  and  impoverished  material. 

EXPLOSIVES. 

From  a  brief  review  of  one  of  the  most  interesting 
arts  of  peace  we  will  pass  to  one  of  the  principal 
industries  of  war.  The  methods  of  production  of 
explosives  are  so  closely  allied  to  those  of  the  coal 


TO    CHEMICAL    SCIENCE  45 

tar  dyes  that  without  much  modification  of  plant 
the  dye  maker  can  turn  his  attention  to  the  war 
industry.  We  will  not  go  so  far  as  to  suggest  that 
the  development  of  the  dye  industry  of  the  Germans 
was  part  of  their  plan  of  preparations  for  war, 
but  they  have  undoubtedly  been  able  to  take 
advantage  of  the  existence  of  their  great  factories 
for  fine  chemicals  and  dyes  in  this  connection.  From 
the  discovery  of  pulvis  fulminans  by  Roger  Bacon 
in  the  thirteenth  century,  the  invention  of  gunpowder 
and  guns  by  Swartz,  the  monk  of  Cologne,  in  the 
fourteenth,  and  the  first  use  of  cannon  in  ships  in 
the  sixteenth  century,  there  was  little  development 
in  the  science  or  industry  of  explosives  until  the 
nineteenth  century;  then,  of  course,  the  need  for 
explosives  in  mining  and  engineering  was  far  in  excess 
of  that  for  war.  Our  present  business  is  not  to 
moralise,  but  to  indicate  with  caution  what  science 
has  done  for  an  industry,  the  foundation  of  which 
lies  in  the  realisation,  by  scientific  men,  of  the  causes 
of  explosion.  An  explosive  compound  or  mixture 
is  one  that  can  be  converted  exothermically  and  with 
great  rapidity  into  gaseous  products  which  at  the 
high  temperature  attained  would  occupy  at  ordinary 
pressure  a  much  greater  space  than  that  occupied 
by  the  original  compound  or  mixture.  The  enormous 
pressure  generated  by  sudden  expansion  constitutes 
the  explosive  force,  and  the  principle  involved  has 
led  to  the  utilisation  of  the  explosive  nature  of  a 
number  of  substances  possessing  this  property  which 
might  otherwise  have  been  overlooked.  For  instance, 
it  is  not  at  all  easy  to  bring  about  the  explosion  of 
trinitrotoluene,  or  T.N.T.  It  is  a  relatively  stable 
substance  ;  but  a  study  of  its  nature  and  comparison 
with  picric  acid,  a  similarly  constituted  body  of 
known  explosive  properties,  would  lead  one  to  suppose 
that  it  could  be  detonated  by  percussion. 

In  1832,  Braconnot  demonstrated  the  formation 
of  an  explosive  substance  by  the  action  of  nitric 
acid  on  wood  fibre,  and  in  1845  Schonbein  obtained 
gun-cotton  by  treating  cotton  with  a  mixture  of 
sulphuric  and  nitric  acids.  Its  manufacture,  however, 


46  WHAT    INDUSTRY   OWES 

though  started  in  several  foreign  countries,  was  not 
successful,  the  production  being  unstable  and 
dangerous,  owing  to  lack  of  care  in  the  details  of 
the  operations  involved.  Sir  Frederick  Abel  showed 
not  only  that  must  the  starting  material,  cotton 
waste,  be  carefully  selected,  but  that  thorough  water 
washing  after  nitration  was  an  important  factor. 
The  instability  of  the  Schonbein  material  was  due 
to  the  presence  of  free  acids.  The  introduction  of 
centrifugal  driers  and  of  paper  pulping  machines  for 
breaking  up  the  cotton  fibre  facilitated  the  wash- 
ing process,  and  reduced  the  risk  of  manufac- 
ture. 

Gun-cotton  is  used  for  a  variety  of  military 
purposes,  such  as  filling  subterranean  and  submarine 
mines  and  torpedoes,  and  it  possesses  the  great 
advantage  that  it  can  be  exploded  when  wet,  although 
the  wet  substance  is  safe  for  handling,  transportation, 
and  storage.  When  dry,  it  is  exploded  by  a  primer 
of  fulminate  of  mercury  ;  when  wet,  a  primer  of 
dry  gun-cotton  is  used.  The  explosive  power  of 
gun-cotton  led  to  attempts  being  made  to  use  it  as 
a  propellant,  but  gun-cotton,  as  such,  is  not  suitable 
for  the  purpose  because  its  explosion  is  very  rapid, 
violent,  and  uncertain.  Attempts  to  "  tame  "  it  by 
gelatinisation  with  certain  organic  liquids  met  with 
success  in  the  smokeless  powders  of  Walter  F.  Reid 
and  Vieille.  The  most  remarkable  result  in  this 
direction,  however,  was  achieved  by  Alfred  Nobel, 
who  produced  a  homogeneous  mixture  of  gun-cotton 
and  nitroglycerine  by  the  evaporation  of  a  solution 
of  those  substances  in  acetone.  By  the  modern 
development  of  this  method,  gun-cotton,  nitro- 
glycerine, and  a  small  quantity  of  mineral  jelly  are 
mixed  well  with  acetone,  and  the  resulting  paste 
is  squeezed  through  jets  to  form  continuous  cords, 
which,  when  dry,  have  the  appearance  of  catgut. 
This  is  cordite,  the  propellant  explosive  used  in 
firearms  of  many  sorts  and  sizes. 

Nitroglycerine,  mentioned  above,  was  discovered 
by  Sobrero,  in  1847,  but  its  explosive  properties 
were  not  utilised  until  its  value  was  recognised  by 


TO    CHEMICAL    SCIENCE  47 

Nobel.  It  is  a  fairly  heavy  oily  liquid,  detonating 
violently  by  percussion,  when  struck  a  sharp  blow, 
or  suddenly  heated.  On  account  of  these  propensities 
the  substance,  as  such,  is  seldom,  if  ever,  employed 
at  the  present  time,  but  is  converted  into  a  safer 
form  by  incorporation  with  some  inert  material,  as, 
for  example,  magnesia  alba,  or  kieselghur,  the 
product  in  the  latter  case  being  dynamite.  In  this 
form,  although  a  certain  amount  of  danger  still 
attends  its  use,  it  is  much  safer  than  in  the  free  state. 
Sometimes  nitroglycerine  is  incorporated  with  an 
explosive  diluent,  as  with  collodion  cotton,  to 
produce  blasting  gelatine,  a  body  with  explosive 
power  exceeding  that  of  nitroglycerine ;  while  a 
mixture  of  thinly  gelatinised  nitroglycerine  with  nitre, 
woodmeal,  and  a  trace  of  soda,  gives  us  gelatine 
dynamite,  another  useful  blasting  agent.  Explosives 
of  this  class,  used  largely  in  mining,  quarrying,  and 
civil  engineering  operations,  have  been  specially 
developed  by  Nobel's  Explosives  Company. 

When  we  come  to  consider  the  class  of  substances 
used  for  the  bursting  charge  of  shells,  it  is  difficult 
to  give  any  individual  the  credit  for  their  first  applica- 
tion, or,  shall  we  say,  "  give  the  devil  his  due." 
Picric  acid,  the  oldest  of  these,  was  discovered  in 
1799  by  Welter,  and  its  nature  as  a  derivative  of 
phenol  was  elucidated  by  Laurent  in  1 842.  Preparations 
of  picric  acid  are  used  by  various  countries,  as  a  military 
high  explosive  under  such  names  as  lyddite,  shimose, 
and  melinite.  Its  great  disadvantage  is  that  it  forma 
very  sensitive  and  highly  explosive  salts  when  left 
in  contact  with  metals  for  any  length  of  time.  This 
drawback  is  not  shared  by  T.N.T.,  which  has  come  so 
much  into  use  during  the  war.  The  substitution 
of  T.N.T.  involves  a  loss  of  explosive  power,  but  this 
is  more  than  counterbalanced  by  the  advantages 
gained.  It  is  used  both  alone  and  in  conjunction 
with  other  substances  such  as  aluminium  powder  and 
ammonium  nitrate.  Such  a  mixture  is  ammonal, 
a  safe  but  very  powerful  explosive  employed  by  the 
Austrians.  Another  very  violent  explosive  is  tetra- 
nitroaniline,  discovered  by  Fleurscheim.  It  is  not 


48  WHAT    INDUSTRY    OWES 

very  largely  used,  as  the  materials  required  for  its 
manufacture  are  comparatively  expensive. 

The  whole  industry  is  based  on  science,  and  should 
be  controlled  by  trained  men  of  science  in  every 
department.  It  has  demanded  its  toll  of  human  life, 
in  spite  of  extraordinary  precautions  ;  but  without 
science  that  toll  would  have  been  far  greater,  and 
certain  it  is  that  without  the  search  for  knowledge, 
the  desire  to  experiment,  and  the  power  to  apply 
the  knowledge  gained,  such  an  industry  could  not 
exist. 

CELLULOSE. 

Cellulose. — Cellulose  belongs  to  the  class  of  sub- 
stances known  chemically  as  carbohydrates.  All 
carbohydrates  consist  of  carbon,  hydrogen,  and 
oxygen,  the  second  and  last  occurring  in  the  same 
proportions  as  in  water. 

Cellulose  is  not  affected  by  ordinary  solvents,  but 
is  attacked  by  strong  sulphuric  acid,  yielding  a 
starch-like  body  called  amyloid,  and  is  dissolved  by 
ammoniacal  solutions  of  copper  salts,  from  which 
it  can  be  precipitated  in  an  amorphous  form  by  the 
addition  of  acids.  This  property  constitutes  the  basis 
of  one  method  of  making  artificial  silk.  It  may  be 
mentioned,  incidentally,  that  when  heated  to  200- 
220  deg.  Cent,  with  caustic  potash,  cellulose  is  broken 
down  into  oxalic  acid,  and  large  quantities  of  that 
acid  are  made  in  this  way.  Sawdust  is  fused  with 
potash  in  iron  pans  ;  the  melt  when  cold  is  extracted 
with  water,  and  the  oxalic  acid  is  precipitated  as  the 
insoluble  calcium  salt  from  which  it  is  subsequently 
liberated  by  the  action  of  sulphuric  acid.  This 
process,  which  was  discovered  by  Gay-Lussac  in  1829, 
and  was  first  employed  on  the  manufacturing  scale 
by  Dale  in  1856,  is  far  cheaper  than  the  older  method 
of  oxidising  sugar  or  starch  with  nitric  acid. 

The  cellulose  industry  is  held  to  include  the  manu- 
facture of  cotton,  linen,  paper  and  pasteboard,  and 
hemp  and  jute  articles.  We  do  not  claim  much  in 
the  way  of  debts  to  science  in  connection  with  the 


TO    CHEMICAL    SCIENCE  49 

manufacture  of  cotton  and  linen,  but  will  choose 
paper  and  pasteboard  for  our  purpose,  and  then  refer 
briefly  to  artificial  silk  and  celluloid. 

Paper  may  be  regarded  as  one  of  the  civili- 
sing agents  in  the  existence  of  man.  It  is  diffi- 
cult to  imagine  what  progress  the  world  would 
have  made  without  it.  The  early  history  of  paper 
is  obscured  by  conflicting  records.  It  is  believed 
to  have  been  used  in  China  long  before  the  Greeks 
and  Romans  ceased  to  use  papyrus,  but  according 
to  M.  Terentius  Varro,  a  voluminous  writer  contem- 
porary with  Cicero,  the  invention  was  devised  at 
Alexandria  on  the  conquest  of  Egypt  by  Alexander 
the  Great  (B.C.  331).  It  was  in  use  in  Arabia  over 
1000  years  ago,  and  the  Crusaders  are  said  to  have 
brought  the  industry  to  Europe.  The  earliest  MS. 
on  cotton  paper  in  the  Bodleian  Collection  in  the 
British  Museum  is  dated  1049,  while  one  on  the  same 
material  in  the  Library  of  Paris  is  dated  1050.  Paper 
made  of  linen  rags  was  in  use  here  in  1170.  The 
Moors  are  credited  with  having  introduced  the 
industry  into  Spain,  where  12th  century  specimens 
still  exist.  The  first  paper  mill  in  this  country  was 
established  by  Tate,  in  Hertfordshire,  in  the  reign 
of  Henry  VII.,  who  visited  it,  and  the  first  important 
one  was  started  at  Dartford,  in  Kent,  in  1588,  or 
thereabouts,  when  Queen  Elizabeth  granted  a 
monopoly,  for  gathering  rags  and  making  paper, 
to  Spielmann,  the  Court  Jeweller. 

Until  the  end  of  the  18th  century  paper  was  made 
by  tearing  and  beating  rags  to  pulp  in  a  machine, 
dipping  a  wire  sieve  into  the  pulp,  transferring  the 
mass  to  a  felt  and  pressing  it  in  moulds  of  various 
sizes.  About  1800  a  Frenchman  devised  a  method 
of  making  it  in  a  continuous  web,  which  he  introduced 
into  England,  where  it  was  steadily  improved  until 
about  1860,  by  which  time,  for  all  ordinary  purposes, 
it  had  superseded  the  old  hand-made  method, 
although  the  latter  is  still  employed  for  bank  notes, 
bonds,  ledgers,  and  important  documents. 

With  the  introduction  of  machine-made    papers 


50  WHAT    INDUSTRY    OWES 

the  output  has  been  vastly  increased,  the  cost  reduced, 
and  the  variety  extended  to  such  a  degree  that  there 
are  now  probably  more  than  20,000  kinds.  In  1820 
the  machines  produced  paper  at  the  rate  of  about 
40ft.  per  minute  ;  the  most  modern  can  now  exceed 
500ft.  per  minute.  Before  1860,  paper  consisted 
almost  entirely  of  rags,  but  about  that  time  an 
Englishman  introduced  the  use  of  esparto,  Macrochloa 
(or  Stipa)  tenacissima,  a  grass  also  employed  for  making 
mats,  nets,  baskets,  &c.,  of  which  the  consumption  in 
paper-making  is  normally  about  200,000  tons  a  year, 
at  £4  to  £4  10s.  per  ton,  almost  all  of  it  coming  to  this 
country  for  the  production  of  fine  printing  papers. 
Over  400  different  materials  have  been  tried  in  the 
industry,  but  rags  and  esparto  are  the  chief  for  good 
papers.  Since  the  year  1880,  chemical  wood  pulp 
has  been  used  as  the  chief  material  for  middling 
kinds,  and  more  recently  mechanical  wood — made  by 
crushing  wood  between  rollers  or  by  pressing  it 
against  a  grindstone — mixed  with  varying  quantities 
of  chemical  wood  pulp,  has  been  employed  for  the 
cheapest  newspapers  and  common  printings. 

Science  has  played  an  important  part  in  the 
development  of  the  paper  industry.  The  introduction 
of  cheap  bleaching  agents  such  as  chloride  of  lime 
to  which,  as  a  by-product  of  the  Leblanc  process 
we  have  already  referred,  has  effected  considerable 
improvements  and  economies,  while  the  utilisation  of 
esparto  and  wood  has  been  made  practicable  only 
by  scientific  research,  the  processes  evolved  from  which 
we  will  now  outline. 

Wood  fibre  is  a  lignocellulose,  a  compound  of 
cellulose  and  a  complex  substance  called  lignone, 
which  acts  apparently  as  a  binding  material.  The 
forest  wood  is  deprived  of  its  bark  and  cut  across  the 
grain  into  small  chips,  which  are  cleaned  and  then 
boiled  at  high  temperature,  under  pressure,  in  a 
solution  of  caustic  soda.  From  coniferous  wood  the 
yield  of  cellulose  is  about  one-third  of  the  weight 
of  the  prepared  wood  treated,  the  other  two-thirds 
being  taken  up  by  the  alkaline  solution.  The  caustic 
soda  required,  amounting  to  about  20  per  cent,  of 


TO    CHEMICAL    SCIENCE  51 

the  weight  of  the  wood,  is  recovered  by  evaporating 
the  spent  liquor,  incinerating  the  residue  and  treating 
a  solution  of  the  ash  with  lime.  The  organic  matter 
in  the  residue,  on  burning,  provides  a  good  deal  of 
the  heat  necessary  for  evaporating  the  solution. 
The  process,  however,  has  one  disadvantage  in  the 
fact  that  a  proportion  of  the  cellulose  is  destroyed 
by  the  action  of  the  strong  alkali.  In  order  to  obtain 
better  yields  two  modifications  have  been  introduced 
comparatively  recently.  One  consists  in  the  sub- 
stitution of  sodium  sulphide  for  the  caustic  soda, 
the  sulphide  being  prepared  on  the  spot  by  the  reduc- 
tion of  sulphate  of  soda  with  the  residue  obtained 
by  evaporating  the  spent  alkali.  The  cycle  of 
operations  is  then  completed  by  making  up  the 
working  loss  of  sodium  sulphide  by  the  addition  of 
sulphate  of  soda  to  the  residue  before  incineration. 
The  other  modification  consists  in  the  application 
of  an  acid  hydrolysing  agent  instead  of  the  alkali. 
The  acid  substance  employed  is  a  solution  of  calcium 
or  magnesium  bisulphite  containing  approximately 
4  per  cent,  of  sulphur  dioxide.  This  solution  is 
prepared  by  passing  pyrites  gases  up  a  tower  filled 
with  calcite  or  dolomite  down  which  water  is  trickling. 
The  cost  of  the  process  is  slightly  higher,  but  not  out- 
of  proportion  to  the  increased  yield  of  cellulose. 

The  cellulose  obtained  by  either  of  the  methods 
is  mashed  to  a  pulp,  washed  free  from  adhering  liquor, 
and  bleached  with  chloride  of  lime  and  sulphuric 
acid,  before  being  utilised  in  the  manufacture  of 
paper.  Those  who  are  interested  in  this  subject  may 
be  invited  to  study  the  series  of  articles  on  "  Paper 
Making,"  which  appeared  in  Vol.  CXX.  of  THE 
ENGINEER. 

"  Artificial  Silk" — The  production  from  cellulose 
of  materials  resembling  silk  is  the  result  of  many 
years  of  scientific  research  and  costly  experiment. 
In  1889  the  Comte  de  Chardonnet  produced  the 
first  artificial  silk  by  nitrating  cellulose  and  dissolving 
the  resulting  product  in  a  mixture  of  alcohol  and 
ether,  thereby  obtaining  a  viscous  liquid  which  he 
forced  through  holes  of  very  small  diameter  into  water. 


52  WHAT    INDUSTRY    OWES 

The  threads  thus  produced  were  then  subjected  to 
the  reducing  action  of  ammonium  sulphide  and  con- 
verted into  an  amorphous  cellulose  having  the 
appearance  of  silk. 

The  method  now  extensively  used  is  that  devised 
by  Cross  and  Bevan,  who  have  contributed  largely 
to  the  existing  knowledge  of  the  chemistry  and 
technology  of  cellulose.  The  starting  material, 
wood  pulp,  is  treated  successively  with  caustic  soda 
solution  and  carbon  bisulphide,  the  viscous  mass 
thus  obtained  being  forced  through  small  apertures, 
from  which  are  produced  filaments  which  are  spun 
into  a  fine  material  also  closely  resembling  silk. 

Celluloid — a  very  useful  substitute  for  horn, 
tortoiseshell,  ivory,  &c. — was  first  made  in  1869 
by  treating  nitrocellulose  with  camphor  and  alcohol. 
Its  inflammability,  however,  has  proved  to  be  a 
very  serious  drawback,  attempts  to  overcome  which 
have  met  with  some  success.  By  the  substitution 
of  acetate  of  cellulose  for  cellulose  itself  in  the  process, 
a  non-inflammable  product — sicoid  or  cellon — is 
formed  which  for  some  purposes  is  more  useful 
than  celluloid. 


TO    CHEMICAL    SCIENCE  53 


CHAPTER  V. 
OILS,  FATS  AND  WAXES. 

OILS  may  be  divided  into :  (a)  animal,  including 
whale  and  fish  oils,  stearin,  which  is  mainly  obtained 
from  beef  and  mutton  suet,  and  neats-foot  oil  from 
the  feet  of  cattle  ;  (ft)  vegetable,  such  as  olive,  linseed, 
cotton  seed,  maize,  palm,  rape,  castor,  and  turpentine, 
and  essential  oils  ;  and  (c)  mineral  oils,  so-called,  such 
as  petroleum,  ozokerite,  and  shale.  It  is  difficult  to 
make  a  sharp  division,  however,  for  the  reason  that 
some  are  obtained  from  more  than  one  of  these  sources  ; 
for  instance,  stearin  exists  in  the  vegetable  kingdom, 
and  petroleum  is  certainly  derived  from  the  products 
of  long  submerged  fish  life.  The  tar  oils  we  have 
already  noticed  in  dealing  with  coal  and  coal  gas. 
Among  the  most  useful  substances  at  our  disposal 
oils  are  employed  as  fuel,  illuminants  and  lubricants, 
and  provide  us  with  material  for  food  and  medicine, 
as  well  as  for  the  manufacture  of  paints  and  varnishes, 
polishes  and  perfumes. 

Oil  has  been  defined  as  a  neutral  fatty  substance, 
liquid  at  ordinary  temperatures  ;  but  although  we  are 
not  satisfied  with  the  definition,  we  will  not  attempt 
to  improve  upon  it,  preferring  rather  to  proceed  with 
our  task  of  indicating  th°  influence  of  science  in  the 
vast  field  of  industry  involved.  That  influence  has 
been  more  marked  in  the  direction  of  improvement 
and  adaptation  rather  than  of  new  and  striking  dis- 
covery. In  some  cases,  however,  scientific  principles 
have  been  applied  to  the  fundamental  processes  of 
oil  production,  with  the  result  that  substances  at  one 
time  ignored  as  valueless  have  become  the  source  of 
products  now  regarded  as  indispensable,  while  the 
science  of  geology  has  rendered  inestimable  service  in 
locating  and  surveying  sources  of  mineral  oil ;  indeed, 

E  2 


I 

54  WHAT    INDUSTRY   OWES 

a  knowledge  of  economic  geology  is  essential  to  all 
mining  engineers. 

The  world's  output  of  petroleum  before  the  war  was 
probably  not  far  short  of  350,000,000  barrels  of  42 
gallons,  of  which  about  two-thirds  were  produced  in 
the  United  States.  Dame  Nature  seems  anxious  to 
get  rid  of  it  as  if  it  were  the  offensive  exudation  of  a 
deep-seated  abscess.  If  nothing  could  be  profitably 
extracted  from  it  we  might  well  wish  it  to  remain  in 
the  bowels  of  the  earth,  counting  it  nothing  but  a 
nuisance  when  it  came  to  the  surface.  Science  can 
at  least  claim  to  have  made  it  useful,  seeing  that  by 
the  process  of  fractional  distillation  this  disagreeable 
natural  substance  can  be  made  to  yield  in  enormous 
quantities  such  valuable  products  as  illuminating  gas, 
motor  spirit,  cleaning  spirit,  kerosene  or  lamp  oil, 
paraffin  wax,  vaseline,  and  a  viscid  residue  used  as 
fuel.  The  crude  petroleum  itself  would  be  useless  for 
any  of  the  purposes  to  which  its  derivatives  are 
applied,  mainly  on  account  of  its  highly  volatile 
constituents,  which  are  a  source  of  danger  in  transport 
and  storage,  owing  to  the  inflammable  nature  of  the 
vapour  arising  from  it.  The  crude  oil  is  conveyed  by 
pipe  lines,  in  some  cases  over  a  distance  of  several 
hundred  miles,  to  the  refinery,  where  it  is  distilled  into 
temperature  fractions.  The  lighter  fractions  are 
purified  by  washing  with  sulphuric  acid,  alkali  and 
water  ;  while  sulphur,  when  it  occurs  in  objectionable 
quantity,  must  be  removed  by  means  of  copper  oxide. 
Among  the  higher  fractions  lubricating  oil  is  purified 
by  nitration  through  animal  charcoal. 

The  lightest  fraction,  cymogene,  which  requires 
special  cooling  and  pressure  for  its  condensation,  is 
used  in  ice-making  machines.  Other  fractions 
obtained  are  rhigolene,  the  illuminant  used  in  the  pen- 
tane  standard  lamp,  and  as  a  local  anaesthetic  in  surgery; 
gasolene,  employed  for  the  carburation  of  water  gas 
for  illuminating  purposes,  for  making  "  air  gas,"  and 
as  a  solvent ;  ligroin,  also  a  solvent ;  benzine  or  petrol, 
which  supplies  us  with  motor  spirit ;  and  kerosene  or 
lamp  oil.  Among  other  products  may  be  mentioned 
paraffin  wax,  which,  with  an  admixture  of  stearic 


TO    CHEMICAL    SCIENCE  55 

acid,  is  used  for  the  manufacture  of  candles,  solar  oils, 
various  grades  of  lubricants,  and  vaseline.  The 
quantity  of  lighter  fractions  can  be  increased  if 
desired  by  the  "  cracking "  of  the  more  complex 
bodies. 

Astatki,  the  residue  from  the  distillation  of  Russian 
petroleum,  yields,  on  distillation,  an  excellent  illumi- 
nating gas,  besides  quantities  of  benzol,  toluol, 
naphthalene,  anthracene,  and  pitch. 

The  shale  oil  industry,  founded  by  James  Young, 
of  Kelly,  in  1851,  which  produces  valuable  quantities 
of  niuminating  and  lubricating  oils,  ammonia,  and 
paraffin  wax,  depends  in  a  similar  manner  on  scientific 
operations. 

We  claim  less  for  science  in  the  extraction  of 
animal  and  vegetable  oils,  which  has  been 
practised  since  time  immemorial,  but  must  place  to 
the  credit  side  of  the  account  the  responsibility  for  the 
differentiation  and  classification  of  such  oils,  the 
selection  of  then*  most  useful  applications,  with 
methods  of  purification  and  of  analysis  and  valuation. 

Vegetable  oils,  such  as  linseed  oil — a  so-called 
drying  oil — and  turpentine  are  used  as  vehicles  in  the 
manufacture  of  paints  and  oil  varnishes.  The  paint 
industry  has  derived  great  benefit  from  science  in  the 
discovery  and  application  of  new  pigments,  and  in  the 
improvement  of  the  older  methods  of  making  pig- 
ments. Turpentine  is  the  starting  material  for  the 
manufacture  of  artificial  camphor,  a  synthesis  that  is 
a  credit  to  organic  chemistry,  and  although  the 
artificial  product  cannot  as  yet  be  made  to  compete 
with  the  natural  substance,  it  renders  good  service 
in  keeping  down  the  price  of  natural  camphor,  of  which 
the  production  is  practically  monopolised  by  the 
Japanese.  Other  vegetable  oils,  such  as  olive  oil, 
rape  oil,  maize  oil,  and  castor  oil,  are  employed  as 
lubricants,  whilst  some  are  good  illuminating  oils. 

The  essential  oils,  of  which  oil  of  turpentine  is  an 
example,  are  vegetable  oils  used  in  many  cases  as 
perfumes.  There  are  three  methods  of  winning  the 
essential  oils :  (1)  by  distillation  with  steam ;  (2)  by 
pressure  of  the  plant  substance  and  (3)  by  extraction 


56  WHAT    INDUSTRY    OWES 


with  suitable  solvents.  Science  has  entered  largely 
into  the  essential  oil  industry  by  finding  the  con- 
stitution of  many  of  the  odoriferous  principles,  which 
have  afterwards  been  successfully  made  in  the  labora- 
tory from  simple  materials.  In  some  cases,  where  the 
actual  substances  have  not  been  made,  very  close 
imitations  have  successfully  competed  with  the 
natural  products.  Examples  of  the  first  are  terpiriol, 
which  is  the  important  constituent  of  Lily  of  the  Valley, 
and  coumarin,  New  Mown  Hay  and  Jockey  Club  ; 
whilst  in  the  second  class  we  have  such  substances  as 
ionone  and  nitrobenzene  substitutes  for  essence  of 
violets  and  oil  of  bitter  almonds  respectively. 

SOAP  AND  CANDLES. 

The  soap  and  candle  industries  must  now  be 
regarded  as  offshoots  of  the  oil  industries.  Their  origin 
is  remote,  but  it  was  not  until  1813,  when  Chevreul 
published  his  remarkable  researches  on  the  composi- 
tion of  oils  and  fats,  that  anything  was  known  of  the 
true  nature  of  the  processes  involved  in  their  manu- 
facture. Nowadays  the  chemist  should  be  in  para- 
mount control  of  their  production.  The  recovery  of 
glycerine,  which  at  one  time  flowed  into  our  rivers 
and  streams  as  a  waste  product,  was  a  scientific 
achievement  of  far-reaching  importance,  as  we  have 
indicated  in  our  remarks  on  explosives,  while  its  use 
in  medicine  is  considerable.  Incidentally  we  may 
mention  also  that  glycerine,  mixed  with  water, 
prevents  evaporation  and  freezing,  and  this  property 
finds  application  in  the  mechanism  of  gas  meters. 

Both  animal  and  vegetable  oils  are  used  in  the 
manufacture  of  soap  and  candles.  When  fats  and  oils 
— such  as  tallow,  palm  oil,  olive  oil — are  boiled  in  large 
cast  iron  pans  with  caustic  alkali,  they  become  decom-' 
posed  and  yield  an  alkaline  salt  of  the  fatty  acid — soap 
and  glycerine.  The  excess  of  alkali  and  the  glycerine 
are  separated  by  the  addition  of  a  solution  of  common 
salt ;  the  soap,  being  insoluble  in  the  brine,  rises  to  the 
top,  and  is  ladled  out  as  a  granular  curdy  mass,  run 
off  into  frames — boxes — to  cool  and  solidify.  Hard 
soaps,  such  as  curd  and  yellow  soap,  are  compounds 


TO    CHEMICAL    SCIENCE  57 

with  soda,  consisting  of  about  26  per  cent,  of  water, 
7  per  cent,  of  soda,  and  66  per  cent,  of  fatty  acids, 
with,  in  the  case  of  yellow  soap,  a  small  percentage 
of  resin.  Soft  soaps  are  compounds  with  potash,  or 
potash  and  soda,  with  fatty  acids  derived  from  drying 
oils,  such  as  whale  and  seal  oils,  linseed,  &c.  With 
regard  to  the  water  content  of  hard  soap  it  has  been 
rumoured  that,  since  soaps  containing  as  much  as 
90  per  cent,  of  water  have  been  encountered,  it 
appears  to  be  the  aim  of  some  soap  makers  to  cause 
water  to  stand  upright. 

CANDLES. 

The  old  tallow  dips,  prepared  by  dipping  a  wick 
repeatedly  into  melted  tallow,  gave  rise,  on  burning, 
to  a  pungent  substance  called  acrolein,  produced  by 
the  decomposition  of  the  glycerine  combined  in  the 
tallow.  Modern  candles  are  without  this  disadvan- 
tage, as  they  contain  no  glycerine,  the  free  fatty  acids 
from  which  they  are  made  being  liberated  from  the 
fat  either  by  the  hydrolytic  action  of  sulphuric  acid, 
or  by  precipitation  of  the  lime  salt  and  its  subsequent 
decomposition  with  sulphuric  acid.  The  fatty  acid — 
e.g.,  stearic  or  palmitic  acid — so  prepared  is  melted  and 
cast  round  about  wicks  in  moulds  of  pewter  or  tin,  or 
sometimes  of  glass,  supported  in  a  wooden  frame,  the 
upper  part  forming  a  trough.  The  wicks  are  arranged 
taut,  the  wax  is  poured  in,  cooled  with  water  to  solidi- 
fication, and  removed  as  candles.  All  sorts  of  waste 
fats,  such  as  those  from  wool  washing  and  glue  making, 
are  used  for  making  candles,  the  free  acid  being 
extracted  by  treating  the  fat  with  sulphuric  acid. 

These  industries  furnish  examples  of  the  utilisation 
of  waste  products.  The  soap  used  for  cleansing 
purposes  in  yarn  mills  is  recovered  by  precipitating 
the  soap  from  waste  liquids  with  lime,  and  pressing 
the  precipitate  into  briquettes,  from  which  sufficient 
gas  can  be  obtained  by  distillation  to  light  the  mills. 
Efforts  are  at  the  present  time  being  made  to  recover 
fat  from  sewage,  mainly  for  the  sake  of  the  glycerine 
content. 


58  WHAT    INDUSTRY    OWES 

EDIBLE  FATS. 

The  invention  of  butter  substitutes,  now  popularised 
by  prevailing  conditions  and  the  need  for  the  exercise 
of  economy,  is  due  to  the  chemist.  These  substances 
are  commonly  made  by  mixing  intimately  a  solid 
animal  fat,  such  as  stearin,  with  some  vegetable  oil, 
such  as  cotton  seed  or  cocoanut  oil,  and  milk.  The 
use  of  solid  animal  oil  for  this  purpose  absorbs  some 
of  the  raw  material  formerly  available  to  the  soap 
maker,  but  the  deficiency  has  been  made  good  by  the 
conversion  of  the  plentiful  supply  of  vegetable  oils, 
such  as  olive  oil,  into  solid  fats  by  hydrogenation  in 
the  presence  of  finely  divided  nickel,  to  which  we 
referred  in  dealing  with  that  metal. 


TO    CHEMICAL    SCIENCE  59 


CHAPTEB  VI. 
LEATHER, 

UP  to  the  close  of  the  eighteenth  century  the 
progress  of  industry  was  slow  but  sure,  much  of  it 
based  undoubtedly  011  the  workings  of  great  minds 
and  patient  inventive  genius,  and  much  again  on 
chance  discovery ;  but  the  nineteenth  century 
marked  an  epoch  of  development,  definitely  hastened 
by  the  advance  made  simultaneously  in  mechanical, 
physical,  chemical,  and  biological  science.  Yet  when 
we  consider  all  that  was  done  in  ancient  times,  for 
example,  in  the  winning  of  metals,  in  the  dyeing  of 
fabrics,  in  agriculture  and  the  domestic  arts,  we 
are  forced  to  marvel  at  the  vast  amount  of  knowledge 
and  experience,  commonly  referred  to  as  empiricism, 
accumulated  for  centuries  before  the  advent  of 
modern  science.  We  are  also  convinced  that  there 
is  no  finality  in  the  matter,  and  that  what  appears 
to  be  ideal  to-day  will  be  improved  upon  to-morrow 
or  the  day  after. 

An  ancient  industry  is  the  manufacture  of  leather, 
which  had  seemingly  reached  the  highest  degree 
of  efficiency  centuries  ago  if  one  may  judge  by  exist- 
ing specimens.  To  the  modern  chemist,  however,  the 
subject  is  open  to  further  investigation,  involving 
problems  directed  to  the  speeding  up  of  production 
and  decrease  of  cost  without  diminishing  the  quality — 
aims  not  easily  attained,  as  many  have  learned  from 
personal  experience.  In  fact,  one  of  our  leading 
authorities  has  recently  expressed  the  opinion  that 
the  science  of  this  important  industry  is  but  in  its 
infamy.  We  are  reassured,  however,  by  the  statement 
that  the  work  of  Professor  H.  R.  Procter  and  the 
Leather  Department  of  the  University  of  Leeds,  was 
largely  the  factor  which  rendered  it  possible  for  the 


60  WHAT    INDUSTRY   OWES 

nation  to  supply  the  enormously  increased  demand 
for  the  military  equipment  of  the  Allied  Armies, 
including  boots,  belts,  leggings,  saddlery,  traces, 
dressed  sheep  skins,  and  numerous  minor  require- 
ments, besides  the  driving  belts  of  the  munition 
factories.  With  such  a  demand  to  meet,  the  price 
for  the  time  being  of  leather  for  furniture,  port- 
manteaux, gloves,  book-binding,  and  parchment  is 
naturally  high. 

The  processes  whereby  raw  hides  are  converted 
into  useful  and  durable  material  by  treatment  with 
various  solutions  of  substances  of  animal,  vegetable 
and  sometimes  mineral  origin,  are  distinctly  chemical 
and  biological.  They  are  investigated  and  explained 
by  research,  and  modified  and  superseded  by  better 
processes,  so  far  as  the  increase  of  knowledge  admits, 
while  accidental  impurities  of  a  harmful  nature  in 
the  liquors  employed  can  be  traced  and  their  presence 
avoided. 

The  hydrochloric  acid  washing  given  to  hides 
that  have  been  unhaired  by  lime,  to  free  them  from 
that  substance,  is  clearly  an  operation  of  a  scientific 
nature,  and  is  also  the  chemical  investigation  of  the 
water  supply,  the  quality  of  the  water  being  important. 
The  science  of  bacteriology  has  rendered  invaluable 
assistance  in  furthering  our  knowledge  of  puering — 
the  process  of  softening  hides  prior  to  tanning. 
The  changes  involved  in  the  old  process  of  treating 
the  unhaired  and  washed  hides  with  an  infusion  of 
dog -dung  have  been  investigated  very  thoroughly  by 
scientific  methods,  and  have  been  shown  to  be  the 
result  of  bacterial  action.  Patents,  founded  on  this 
knowledge,  have  been  taken  out  for  the  use  of 
artificial  cultures  of  bacteria  instead  of  the  obnoxious 
infusion  referred  to.  Some  of  these  methods  give 
excellent  results,  and  would  doubtless  be  more  gener- 
ally adopted  were  it  not  for  the  conservatism  of  the 
workman  and  his  dislike  of  the  trouble  necessitated 
by  a  change  of  procedure. 

The  oldest  method  of  treating  skin  and  hide  for 
the  purpose  of  preservation  in  a  flexible  state,  which 
consisted  in  kneading  with  fatty  substances,  is  of 


TO    CHEMICAL    SCIENCE  61 

historic  interest  only,  though  chamois  leather  is 
still  prepared  with  oil.  Next  in  chronological  order 
conies  vegetable  tanning,  still  very  extensively  used, 
the  tanning  liquor  being  an  infusion  of  some  bark. 
e.g.,  of  oak  or  willow.  Up  to  the  end  of  the  eighteenth 
century  the  prepared  hides  were  simply  soaked  in  a 
strong  infusion  of  the  tan,  but  about  that  time  Seguin, 
a  Frenchman,  introduced  a  method  for  soaking  the 
hides  successively  in  tan  liquor,  or  ooze,  of  increasing 
strength,  the  untanned  hide  going  first  into  the 
weakest,  the  completely  tanned  material  being  taken 
from  the  strongest  liquor.  By  this  means  thorough 
permeation  by  the  tan  liquor  was  ensured,  and  the 
quality  of  leather  considerably  improved.  This 
method  was  patented  in  England  by  William  Desmond 
in  1795. 

Sir  Humphry  Davy  investigated  the  process  of 
tanning  with  useful  results,  indicating  the  nature 
of  the  action  between  the  hide  and  the  tanning 
material,  but  only  recently  has  science  obtained  a 
hearing  in  the  industry.  The  reason  for  this  is  not 
far  to  seek ;  the  changes  involved  in  tanning  are 
exceedingly  complex  in  character,  and  depend  to  a 
large  extent  upon  the  properties  of  substances  in  a 
colloidal  condition.  Examples  of  this  state  are  to 
be  found  in  solutions  of  gelatine  and  starch  having 
properties  different  from  ordinary  solutions,  such 
as  that  of  setting  with  the  formation  of  a  jelly. 
The  scientific  study  of  the  colloidal  state  is  now  being 
more  vigorously  pursued,  and  as  our  knowledge 
of  it  increases  we  may  expect  further  advances  in 
the  leather  industry. 

Mineral  tannages,  of  which  alum  was  the  first 
known,  are  also  of  interest.  The  "  tawing  "  solution 
contains  alum  and  common  salt,  the  latter  serving  to 
counteract  the  swelling  of  the  hide  produced  by  the 
free  acid  in  the  alum  solution.  Salts  of  the  metals 
iron  and  chromium,  chemically  similar  to  aluminium, 
have  been  used  for  tanning,  and  although  iron  salts 
have  no  application  as  tannages  at  the  present  time, 
chrome  tanning  is  a  very  important  industry,  founded 
and  reared  upon  scientific  knowledge.  Many  patents 


62  WHAT   INDUSTRY   OWES 

have  been  taken  out,  inchiding  those  by  Knapp  in 
1858,  by  J.  W.— later  Sir  J.  W. — Swan,  by  Hein- 
zerling  in  1879  (the  first  commercially  successful 
process  introduced  into  England)  and  that  by 
Augustus  Schultz,  a  New  York  dye  works  chemist,  in 
1884.  Valuable  scientific  work  has  also  been  done  in 
this  branch  by  Eitner  and  by  Procter.  A  soft  and 
durable  leather  can  be  produced  which  will  fix  an  acid 
dye  without  a  mordant. 

Leather  cloth  substitutes  for  leather,  used  for 
covering  furniture,  for  bookbinding,  stationery  cases, 
pocket  books,  and  many  other  useful  articles,  are 
also  produced  under  scientific  supervision.  This 
industry,  however,  with  that  of  linoleum  and  similar 
material,  might  have  been  dealt  with  as  branches  of 
the  oil  industry  had  we  attempted  to  deal  more 
comprehensively  with  that  subject. 

Apart  from  skins  and  hides  there  are  other  products 
of  the  slaughter-house,  such  as  horn,  blood,  hair  and 
bristles,  waste  wool  and  the  like,  from  which  valuable 
chemicals  such  as  cyanide  are  produced.  Glue,  too, 
is  made  from  the  chippings  of  hides,  horns  and  hoofs, 
which  are  washed  in  lime-water,  boiled,  skimmed, 
strained,  evaporated,  cooled  in  moulds,  cut  into 
convenient  pieces  and  dried  on  nets.  The  processes 
are  nowadays  supervised  by  trained  chemists. 


TO    CHEMICAL    SCIENCE  63 


CHAPTER  VII. 
RUBBER. 

RUBBER,  formerly  commonly  called  caoutchouc, 
was  originally  imported  from  French  Guiana.  It 
was  obtained  from  the  Siphonia  elastica,  and 
from  Brazil,  from  the  Siphonia  or  Hevea  Brazilien- 
sis,  lutea  and  brevifolia,  through  the  port  of  Para, 
and  later  from  the  ficus  elastica,  or  india-rubber 
tree.  It  was  first  brought  to  Europe  in  the  early 
part  of  the  eighteenth  century,  but  it  was  many 
years  before  its  usefulness  was  realissd.  Priestley, 
the  discoverer  of  oxygen,  suggested  its  use  for  re- 
moving pencil  marks  and,  in  1791,  Samuel  Piat 
obtained  a  patent  for  making  waterproof  fabrics  by 
dissolving  caoutchouc  in  spirits  of  turpentine. 
Hancock,  in  1823,  and  Macintosh  followed  on  similar 
lines,  but  the  invention  of  the  vulcanising  process  by 
Charles  Goodyear,  whereby  the  addition  of  sulphur 
gave  it  the  consistency  of  horn,  marked  the  starting 
point  of  still  greater  developments. 

The  rubber  industry  has  recognised  the  importance 
of  scientific  control,  by  botanists  and  chemists,  in 
planting,  cultivation  and  tapping,  with  consequent 
increased  yields.  Chemists  examine  the  latex,  and 
supervise  its  drying  and  preparation  for  use.  The 
variability  of  tensile  strength  is  largely  dependent  on 
the  size  of  the  globules  in  the  latex,  which  is  valued 
accordingly.  No  standards  of  purity  have  been 
established,  but  fine  Para  is  generally  considered 
superior  to  other  varieties. 

For  nearly  sixty  years  chemists  of  all  countries 
have  devoted  much  time  and  labour  to  its  synthetic 
production  in  the  laboratory.  In  1860  Greville 
Williams  isolated  a  compound,  which  he  called 
isoprene,  from  the  products  of  the  distillation  o£ 


64  WHAT    INDUSTRY    OWES 

natural  rubber.  Nineteen  years  later,  Bouchardat 
showed  that  a  substance  very  closely  resembling 
rubber  could  be  reproduced  from  isoprene  by  the 
action  of  strong  hydrochloric  acid,  and  that  by  the 
action  of  heat  alone  isoprene  yielded  turpentine. 
The  work  of  the  French  chemist  was  confirmed,  in 
1884,  by  Professor — now  Sir—William  Tilden,  who 
suggested  a  formula  for  isoprene,  which  subsequently 
proved  to  be  correct,  and  also  obtained  isoprene  from 
turpentine.  Later,  these  researches  formed  the  basis 
on  which  the  synthetic  rubber  industry  was  founded, 
though  German  chemists,  who  have  also  done  good 
work  in  this  field  of  investigation,  lay  claim  to  having 
established  principles  the  credit  for  which  was  clearly 
not  due  to  them.  Among  other  British  chemists  who 
have  contributed  to  the  investigations  on  the  subject 
may  be  mentioned  Professor  W.  H.  Perkin,  Dr. 
Strange,  and  Dr.  F.  E.  Matthews.  Two  chemically 
different  rubbers  are  produced  :  isoprene -caoutchouc 
and  butadiene -caoutchouc.  The  raw  materials, 
isoprene  and  butadiene,  are  obtained  from  a  variety 
of  substances,  including  turpentine,  isopentane  (from 
the  rhigolene  fraction  of  American  petroleum),  coal 
tar  (the  material  from  this  source  being  para-cresol, 
one  of  the  homologues  of  carbolic  acid),  starch  and 
cellulose.  The  raw  material  is  converted  into 
caoutchouc  by  methods,  involving  (i.)  polymerisation, 
by  heating  under  pressure  with  a  suitable  substance 
such  as  acetic  acid,  and  (ii.)  polymerisation,  by  the 
action  of  sodium.  The  latter  method,  discovered 
almost  simultaneously  by  F.  E.  Matthews  in  England 
and  Harries  in  Germany,  is  the  more  convenient 
and  gives  the  greater  yield,  although  the  resulting 
product  does  not  vulcanise  so  well  as  that  from  the 
former  method.  All  this  is  progress.  As  in  the  case 
of  indigo,  science,  if  successful,  will  help  one  form  of 
industry  to  the  detriment  of  another  ;  the  scientific 
work  on  the  plantations  tends  constantly  to  increased 
yields  and  economical  working,  and  the  artificial 
rubber  has  not  as  yet  displaced  the  natural  either  in 
its  properties  or  in  cost  of  production. 


TO    CHEMICAL    SCIENCE  65 


CHAPTER  VIII. 
MORTAR  AND  CEMENT. 

THE  simplest  and  most  ancient  cementitious 
material  is  mud,  which  is  still  used,  reinforced  by 
sticks  and  grass,  by  African  natives  in  the  construc- 
tion of  their  huts.  Ordinary  mortar  is  made  of 
water,  lime,  and  sand  intimately  mixed  together. 
Science  has  shown  that  there  is  no  chemical  union 
between  the  lime  and  sand ;  that  the  sand  acts 
simply  as  a  diluent,  preventing  undue  shrinkage, 
which  occurs  when  lime  is  used  alone  ;  that  the  setting 
is  due  to  loss  of  water,  and  that  the  hardening  is 
caused  by  the  gradual  formation  of  interlacing 
crystals  of  calcium  carbonate,  which  effectively  bind 
the  material  into  a  coherent  mass. 

Long  before  these  facts  had  been  established, 
experience  had  proved  that  a  pure  or  "  fat  "  lime 
produced  a  better  mortar  than  an  impure  lime.  In 
the  case  of  hydraulic  mortars  and  cements,  however, 
the  knowledge  of  their  structure  and  action  was 
indefinite  until  1887,  when  the  researches  of  Le 
Chatelier  were  published,  though  a  fairly  systematic 
investigation  of  the  nature  of  hydraulic  mortar  or 
rather  of  the  hydraulic  limestones  employed  in  its 
manufacture,  was  made  about  the  year  1756  by 
Smeaton,  whilst  searching  for  the  most  suitable 
binding  material  for  the  foundations  of  the  Eddystone 
Lighthouse,  which  he  had  been  commissioned  to 
rebuild.  He  consulted  his  friend  Cookworthy,  a 
chemist,  who  instructed  him  in  the  analysis  of  lime- 
stones, and  he  found  that  clay  was  an  essential 
constituent  of  a  hydraulic  limestone,  the  poor  lime 
obtained  on  burning  it  being  far  superior  to  fat  lime 
for  making  mortar  intended  to  withstand  exposure 
to  water. 


66  WHAT   INDUSTRY   OWES 

Cements  are  made  by  heating  in  a  furnace  an 
intimate  mixture  of  limestone  or  chalk  and  clay  to  a 
temperature  at  which  clinkering  takes  place.  The 
product  is  broken  up,  finely  ground,  and  put  upon  the 
market  as  cement.  "  Roman  "  cement  was  first  made 
by  James  Parker  in  1796,  by  heating  argillaceous  lime- 
stone containing,  already  mixed,  the  two  necessary 
ingredients.  The  manufacture  of  Portland  cement 
was  founded  on  attempts  to  imitate  Roman  cement, 
using  a  mixture  of  lime  and  clay  instead  of  the 
argillaceous  limestone.  Nothing  was  understood 
of  the  why  and  the  wherefore  of  the  process,  and 
often  the  best  part  of  the  product  was  rejected  in 
the  unslakeable  portions.  Chemical  action  in  the 
furnace  was  unthought  of,  and  even  when  it  was 
evident  to  scientific  men  and  duly  published,  con- 
siderable time  elapsed  before  the  manufacturers 
took  advantage  of  the  efforts  of  science  towards  the 
furtherance  of  their  industry.  It  is  now  known 
that  chemical  action  between  the  lime  and  the  clay 
in  the  furnace  effects  the  formation  of  silicate  and 
aluminate  of  calcium.  When  the  cement  is  treated 
with  water,  these  compounds  are  decomposed  with 
the  production  of  slaked  lime,  and  the  acids  derived 
from  silica  and  alumina.  These  substances  again 
interact,  with  the  formation  of  the  hydrated  silicates 
and  aluminates  as  interlacing  crystals,  giving  tenacity 
to  the  preparation,  with  the  result  that  first  setting 
and  subsequently  hardening  take  place,  these 
phenomena  being  merely  stages  in  one  process. 
Thus  the  researches  of  chemists  have  established 
facts  which  have  been  most  serviceable  to  the  cement 
maker  in  increasing  the  efficiency  of  his  product 
through  the  choice  and  treatment  of  the  best 
materials. 

We  owe  more  than  this,  however,  to  the  study 
of  the  chemistry  of  cement.  It  remained  for  chemists 
to  show  the  dangerous  effect  of  certain  impurities, 
such  as  magnesia,  in  excess,  and  sulphates,  on  the 
resistance  of  cement  to  the  attack  of  water.  Such 
substances  must  be  carefully  excluded  within  well- 
defined  limits.  When  cement  is  used  to  make 


TO    CHEMICAL    SCIENCE  67 

concrete  foundations  exposed  to  sea,  water,  the  mass 
must  be  either  very  compact  and  impervious,  or 
be  covered  with  an  impenetrable  stone  facing,  for 
the  reason  that  sea  water  contains  sulphates  and 
salts  of  magnesium  in  plenty,  and,  consequently, 
if  penetration  by  the  water  takes  place,  the  cement 
decomposes  and  the  life  of  the  structure  is  corres- 
pondingly shortened. 

It  is  obvious  that  for  such  a  substance,  on  which 
the  stability  of  costly  buildings  and  structures  so 
largely  depends,  the  provision  of  a  definite  standard 
specification  became  a  necessity.  The  British 
Standard  Specification  was  formulated  in  1904  by  a 
sub -committee,  appointed  by  the  Engineering 
Standards  Committee,  including  engineers  and  con- 
tractors, chemists,  architects,  manufacturers,  and 
representatives  of  official  bodies  using  large  quan- 
tities of  Portland  cement  for  public  works.  The 
specification  provided  for  both  chemical  and  mechani- 
cal tests,  and,  although  subsequently  modified  in 
the  direction  of  improving  the  quality  of  the  cement 
supplied  under  the  specification,  remains  essentially 
the  same  to-day — a  definitely  scientific  safeguard 
accepted  alike  by  producers  and  users. 

We  have  indicated  how  the  explanation  of  scientific 
phenomena  tends  to  improvement  in  manufacture, 
and  it  is  interesting  to  note  that  a  reason  has  been 
advanced  for  the  use  of  straw  in  the  making  of  bricks 
by  the  Israelites.  It  is  not  a  suitable  binding  material, 
but  Acheson  has  shown  that  clay  is  rendered  more 
plastic  by  the  addition  of  tannin,  and  that  an  extract 
obtained  by  soaking  straw  in  water  produces  the 
same  effect.  The  Israelites  complained,  therefore, 
of  the  hardship  of  working  with  less  suitable  materials, 
while  they  had  to  produce  the  same  tale  of  bricks. 
Possibly  the  use  of  grass  assists  in  the  same  way  the 
African  natives  in  making  their  mud  huts. 


68  WHAT    INDUSTRY   OWES 


CHAPTER  IX. 
REFRACTORY  MATERIALS. 

A  MATERIAL  ia  termed  refractory  when  it  resists 
the  ordinary  treatment  to  which  materials  of  its 
class  are  subjected  ;  it  may  be  a  mineral  which  does 
not  yield  readily  to  the  hammer,  or  an  ore  not  easily 
reduced.  In  recent  times,  however,  the  term  has 
become  specially  associated  with  substances  that  will 
resist  economically  the  temperature  of  a  furnace,  and 
the  corrosive  action  of  other  substances  with  which 
they  come  into  contact.  Refractoriness  may,  there- 
fore, be  a  vice  or  a  virtue,  according  to  circumstances, 
and  a  given  material  may  be  refractory  in  one  process, 
but  break  down  easily  if  employed  in  another. 

The  increased  demand  for  refractory  materials  during 
the  war,  particularly  in  the  manufacture  of  steel  and 
glass,  has  shown  the  need  for  further  scientific  investi- 
gation. Experiment  on  the  large  scale  is  costly, 
especially  if  carried  out  in  an  unscientific  manner. 
The  help  of  chemists  is  therefore  essential  in  deter- 
mining the  composition  and  the  chemical  and  physical 
properties  of  such  substances,  having  in  view  the 
purposes  to  which  they  are  to  be  applied.  The 
work  is  not  confined  to  the  investigation  of  known 
refractories,  but  is  extended  to  the  discovery  and 
utilisation  of  new  refractories  to  cope  with  the  con- 
ditions created  by  their  employment  in  high  tempera- 
ture furnaces. 

Having  selected  a  suitable  material,  from  the 
chemical  point  of  view,  it  is  necessary  to  ascertain 
whether  it  will  withstand,  without  shrinkage,  fusion 
or  softening — and  consequent  deformation — the 
temperature  required  for  the  desired  reaction.  The 
refractory  that  will  last  for  ever  has  yet  to  be  found, 
but  that  with  the  longest  life  is  the  most  economical, 


TO    CHEMICAL    SCIENCE  69 

provided  the  saving  effected  by  the  increased  length 
of  life — renewals  being  less  frequently  required — 
plus  the  saving  of  time  and  labour,  in  more  continuous 
running  of  the  furnace,  is  proportionate  to  any 
additional  cost.  The  subject  has  long  been  treated 
more  or  less  scientifically,  the  older  refractories 
being  classified  into  acid,  basic,  and  neutral  materials^ 
As  examples  of  the  acid  class  we  have  fire-clays,  such 
as  ganister,  the  highly  siliceous  material  used  for 
lining  acid  Bessemer  converters  ;  in  the  basic  class, 
such  substances  as  lime,  magnesia,  and  calcined 
dolomite  ;  while  among  the  neutral  refractories  we 
may  include  gas  carbon  and  graphite.  These  mate- 
rials have  proved  eminently  suitable  for  some  pur- 
poses, but  with  the  use  of  the  electric  furnace  we 
require  substances  still  more  refractory,  and  in  recent 
years  science  has  provided  a  number  of  them. 

Carborundum,  the  extremely  hard  and  refractory 
carbide  of  silicon,  was  first  made  in  1891  by  Acheson, 
who  obtained  it  by  heating  graphite  with  sand  in  the 
electric  furnace,  and  it  is  now  employed  as  a  refractory 
lining  for  such  furnaces,  besides  being  useful  as  an 
abrasive.  It  has  also  been  incorporated  with  cement 
to  give  grip  to  surfaces,  as  on  staircases  subjected  to 
considerable  wear.  Other  modern  refractories  are 
alundum — fused  aluminium  oxide — silicon,  fused 
silica,  zirconia,  and  artificially  made  graphite.  Cru- 
cibles of  graphite,  intimately  mixed  with  sufficient 
clay  to  give  the  mixture  coherence,  are  far  preferable 
for  many  purposes,  and  much  more  durable  than  those 
made  of  clay  alone. 


F  2 


70  WHAT    INDUSTRY    OWES 


CHAPTEB  X. 
GLASS  AND  ENAMELS. 

THE  manufacture  of  glass  dates  from  the  first 
period  of  Egyptian  history.  Egypt,  the  instructor 
of  the  world  in  so  many  arts,  possessed  in  very  early 
times  craftsmen  skilled  in  making,  blowing,  colour- 
ing and  cutting  this  most  remarkable  and  useful 
material.  The  industry  survived  through  the  vicis- 
situdes of  the  country  until  the  time  of  Tiberius 
(A.D.  14-41),  who  brought  Egyptian  glass  workers  to 
Rome,  where  the  art  nourished  until  the  decline  of  the 
empire,  during  which  the  principal  centre  of  manu- 
facture was  transferred  to  Byzantium.  The  value 
attached  to  glass  by  the  ancients  is  indicated  by  the 
circumstance  that  the  industry  was  always  supported 
and  encouraged  by  the  most  powerful  and  influential 
rulers,  migrating  with  their  power  from  one  country 
to  another.  However,  at  the  time  of  the  fall  of 
Constantinople  it  had  become  established  in  various 
centres,  of  which  the  chief  was  Venice,  where  it  soon 
attained  such  proportions  as  to  give  occupation  to 
over  8000  persons. 

In  the  Middle  Ages  the  industry  was  developed  in 
Germany  and  Bohemia,  especially  in  the  latter  country , 
which,  owing  to  the  native  supply  of  pure  quartz, 
ultimately  superseded  Venice  as  the  source  of  the  finest 
glass.  Inl870  glass  making  gave  employment  to  30,000 
workers  in  Bohemia.  The  invention  of  glass  mirrors 
has  been  attributed  to  the  Germans,  the  original 
method  being  to  back  the  glass  with  polished  metal. 
Glass  was  first  used  for  windows  in  England  about 
the  end  of  the  eleventh  century,  and  was  made  here 
in  the  fifteenth,  but  with  little  success  until  about 
1557,  when  French  artisans  were  employed  in  London. 
In  1670  Venetian  workers  were  brought  over  to  make 


TO    CHEMICAL    SCIENCE  71 

the  heavier  and  finer  kinds,  and  in  1771  the  industry 
became  more  firmly  established  by  the  formation  of 
the  British  Plate  Glass  Company,  whose  successors 
are  still  in  existence  at  St.  Helens. 

The  scientific  study  of  glass  was  first  made  on  the 
physical  side,  its  transparency,  permanence,  and  the 
absence  of  crystalline  structure  with  consequent 
birefringence,  combining  to  render  it  an  almost  ideal 
material  for  the  construction  of  the  essential  parts  of 
optical  instruments.  In  fact,  the  science  of  optics, 
with  its  manifold  applications  to  spectacles,  micro- 
scopes, telescopes  and  spectroscopes,  owes  its  exist- 
ence to  our  possession  of  glass.  The  first  investiga- 
tions in  the  chemistry  of  the  subject  were  made  with 
a  view  to  the  improvement  and  better  adaptation  of 
glass  to  optical  purposes.  Up  to  1829  the  only 
varieties  of  optical  glass  were  soda-lime  or  crown 
glass,  potash-lime  or  Bohemian  glass,  and  potash-lead 
or  flint  glass,  also  known  as  crystal  or  strass,  these 
being  made  from  mixtures  of  the  silicates  of  the 
metals  indicated.  Before  that  year  Fraunhofer  and 
Guinand  had  made  experiments  modifying  the  com- 
position of  crown  and  flint  glasses,  and  had  produced 
compound  lenses  with  a  fair  approach  to  achro- 
matism. In  1829,  however,  Dobereiner  produced 
glasses  containing  barium  and  strontium,  metals 
closely  allied  to  calcium,  the  metal  contained  in  lime, 
and  in  1834  Harcourt,  in  England,  commenced  a  long 
series  of  researches  on  the  production  of  new  glasses, 
which — although  the  positive  results  obtained  were 
of  small  value — established  principles  subsequently 
turned  to  good  account  in  the  manufacture  of  special 
kinds  for  thermometers,  laboratory  apparatus,  lamp 
chimneys,  optical  instruments,  and  many  other 
important  articles.  The  next  advance,  an  epoch- 
making  one,  was  begun  about  1880,  when  Schott,  a 
trained  chemist,  the  son  of  a  Westphalian  glass  maker, 
was  encouraged  by  Abbe  to  search  for  new  and 
better  optical  glass.  His  knowledge  of  mineralogy 
served  him  well,  for  instead  of  proceeding  laboriously 
along  the  lines  of  methodical  research,  he  took  almost 
a  direct  road  to  the  desired  goal,  producing  glass  con- 


72  WHAT    INDUSTRY   OWES 

taining  boric  and  phosphoric  oxides  with  alumina  and 
baryta.  Microscopes  designed  for  these  new  glasses 
proved  perfectly  achromatic,  and  in  every  way 
superior  to  the  older  kinds  ;  and  this  striking  advance 
has  doubtless  contributed  enormously  to  the  useful- 
ness of  the  microscope,  and  of  the  microscope  to 
industry  generally. 

Schott  next  turned  his  attention  to  the  solution  of 
the  problems  of  thermal  expansion  and  volume  tem- 
perature hysteresis  of  glass.  Owing  to  its  low  thermal 
conductivity  it  is  important  that  glass  intended  to 
withstand  sudden  changes  of  temperature  should 
have  a  thermal  expansion  as  slight  as  possible,  in 
order  to  hold  against  the  strain  set  up  by  unequal 
temperature  changes,  and  so  that  the  risk  of  cracking 
may  be  minimised  within  reasonable  limits ;  the 
range  of  temperature  change  varying  inversely  as  the 
thermal  expansion.  Pursuing  his  investigations, 
Schott  produced  borosilicate  glasses  with  exceed- 
ingly low  coefficients  of  expansion,  and  capable  of 
resisting  a  sudden  temperature  change  of  over  190 
deg.  Cent.,  whereas  the  ordinary  Bohemian  glass 
would  scarcely  withstand  a  change  of  much  over  90 
deg.  The  borosilicate  glasses  have  therefore  been  of 
service  for  the  construction  of  incandescence  gas 
chimneys,  and  also  of  apparatus  for  laboratory  use  ; 
their  slight  solubility  in  chemical  reagents  constitut- 
ing an  additional  advantage. 

When  a  thermometer  made  of  ordinary  glass  is  heated 
to  a  temperature  much  above  that  of  the  air  the  glass 
bulb,  on  cooling,  does  not  return  immediately  to  its 
original  volume,  and  may  take  months  or  even  years 
to  do  so.  Consequently  if  the  bulb,  before  it  has  re- 
gained its  original  volume,  is  surrounded  by  melting 
ice,  the  thermometer  will  not  register  the  true  melting 
point,  but  a  point,  varying  with  the  thermometer,  from 
0.5  to  1  deg.  Cent,  below  the  correct  temperature  ; 
and  lower  temperatures  in  general  will  not  be  regis- 
tered correctly  until  the  bulb  has  regained  its  original 
volume.  This  defect  was  largely  overcome  by  the 
results  obtained  by  Schott,  whose  Jena  normal  glass 
16111  and  Jena  borosilicate  glass  59111,  when  used  for 


TO    CHEMICAL    SCIENCE  73 

thermometers,  show  a  zero  depression  of  only  about 
0. 05  deg.  Cent,  after  heating  to  100  deg.  Cent.  Owing 
to  their  infusibility,  glasses  of  this  type  can  also  be 
used  for  nitrogen-filled  thermometers,  registering  up 
to  about  575  deg.  Cent. 

The  list  of  new  and  useful  scientific  products  might 
be  much  further  extended  if  we  were  to  deal  with  the 
subject  more  thoroughly,  but  it  would  be  regarded  as 
an  oversight  if  we  omitted  to  mention  fused  silica 
glass,  a  comparatively  recent  invention.  From  pure 
quartz  worked  in  the  oxy-hydrogen  flame  excellent 
glass  is  produced,  having  the  property  of  withstanding 
a  sudden  change  of  temperature  of  over  1000  deg. 
Cent.  Being  highly  resistant  to  chemical  action,  it 
useful  in  the  laboratory  for  many  purposes  for 
which  platinum  was  formerly  employed. 

Until  the  outbreak  of  war  the  production  of  glass- 
ware for  use  in  chemical  investigations  was  almost 
exclusively  in  the  hands  of  Germany  and  Austria. 
Stocks  were  becoming  speedily  exhausted  and  the 
position  would  have  become  serious  for  many  impor- 
tant industries  if  British  chemists  had  not  promptly 
taken  the  matter  in  hand.  They  had  not  merely  to 
imitate  glasses  previously  imported,  but  to  find 
substitutes  for  certain  ingredients  of  batch  mixtures, 
notably  potash,  for  which  also  we  had  hitherto  been 
dependent  on  Germany  and  of  which  supplies  were 
running  low.  The  work  of  Professor  Herbert  Jackson*, 
in  conjunction  with  the  Glass  Research  Committee  of 
the  Institute  of  Chemistry,  was  especially  successful, 
and,  with  the  co-operation  of  a  number  of  well-known 
firms,  laboratory  vessels,  such  as  beakers  and  flasks, 
and  all  ordinary  forms  of  apparatus  are  now  produced 
in  this  country,  having  qualities  in  some  respects 
superior  to  those  of  enemy  origin.  In  some  cases, 
perhaps,  the  products  have  not  quite  the  same  finish 
as  those  of  the  experienced  German  workers,  but  we 
are  convinced  that  the  defects  are  not  radical,  and 
that  given  time,  the  British  makers  will  not  only  equal, 
but  excel  the  German  in  both  quality  and  technique. 

*  Now  Sir  Herbert  Jackson,  K.B.E. 


74  WHAT    INDUSTRY    OWES 


In  addition  to  the  needs  of  the  laboratory,  many  other 
kinds  of  glass  were  required,  and  the  work  was 
extended  to  the  investigation  of  over  forty  varieties 
for  which  formulas  have  been  supplied  to  approved 
firms.  With  shortage  of  labour  and  other  economic 
difficulties,  firms  have  undertaken  with  remarkable 
energy  new  branches  of  work  which  it  is  hoped  they 
will  be  able  to  retain,  in  the  future,  in  the  face  of 
competition  from  our  quondam  enemies. 

Yet  another  problem  has  been  successfully  tackled 
by  Professor  Jackson  for  the  Ministry  of  Munitions, 
viz.,  the  treatment  of  clay  used  for  making  vessels 
employed  in  glass  production. 

For  the  production  of  optical  glass  essential  to  the 
services,  we,  fortunately,  had  well-established  manu- 
facturers, by  whose  praiseworthy  endeavours  the 
output  has  been  sufficient  to  cope  with  the  greatly 
increased  demand.  Professor  Jackson  has  supplied 
formulas  for  batch  mixtures  for  several  important 
varieties  not  hitherto  made  in  this  country.  The 
difficulty  of  securing  supplies  of  suitable  sand  had 
also  to  be  faced,  and  our  mineralogists  and  chemists 
devoted  attention  to  this  question,  with  satisfactory 
results,  the  report  of  Dr.  Boswell,  of  the  Imperial 
College  of  Science  and  Technology,  indicates  that  we 
possess  natural  resources  which  can  be  utilised  by  our 
manufacturers  to  their  advantage.  Research  work 
on  refractories  and  electric  furnace  methods  is  also 
in  progress  at  the  National  Physical  Laboratory. 

In  the  course  of  time  an  enterprising  firm,  with  the 
aid  of  chemists  and  from  indigenous  sources,  produced 
supplies  of  potash  of  high  quality  in  sufficient  bulk 
for  the  imperative  requirements  of  glass  makers,  and 
this  factor  was  of  no  small  consequence,  since  it  is 
admitted  that  for  certain  glasses  potash  is  practically 
indispensable. 

From  the  foregoing,  it  is  evident  that  in  spite  of 
the  antiquity  of  the  industry,  and  the  fact  that  good 
glasses  for  ordinary  and  ornamental  purposes  were 
produced  independently  of  modern  science,  many 
special  glasses  owe  their  origin  entirely  to  scientific 
investigation.  It  is  not  too  much  to  say  that  on  the 


TO    CHEMICAL    SCIENCE  75 

possession  of  such  glasses  in  time  of  war  may  depend 
the  fate  of  many  a  good  ship  and  many  a  good  man. 
Who  can  say,  then,  how  great  is  the  debt  of  the 
industry  to  science  and  of  the  country  to  both  ? 

ENAMELS. 

The  art  of  enamelling  is  of  remote  origin.  We 
have  already  referred  to  its  application  to  pottery  by 
the  Chinese.  It  was  practised  also  by  the  Egyptians 
and  Etruscans,  passing  in  the  course  of  time  to  the 
Greeks  and  Romans  ;  but  we  propose  to  deal  more 
particularly  with  the  enamelling  of  metals,  which 
appears  to  have  been  invented  in  Western  Asia 
and  to  have  traversed  Europe  in  the  early  centuries 
of  the  Christian  era.  The  history  of  the  subject  is 
of  absorbing  interest  to  those  who  regard  it  as  an  art, 
and  much  may  be  gleaned  from  BushelFs  work  on 
"  Chinese  Art,"  published  by  the  Board  of  Education. 
The  Chinese  give  the  credit  for  its  discovery  to 
Constantinople ;  the  similarity  between  the  methods 
of  the  Chinese  and  the  Byzantine  enamellers  is  held 
to  support  this  opinion.  We  are  concerned  here,  how- 
ever, with  the  utilitarian  rather  than  the  artistic 
applications  of  enamels.  We  use  them  in  the  manu- 
facture of  badges,  watch  and  clock  faces,  and  on 
surfaces  exposed  to  weather  (advertisements),  on  th« 
blades  of  exhaust  fans,  on  baths  and  domestic  utensils, 
and  on  vessels  employed  in  chemical  industry. 

An  ordinary  enamel  may  be  prepared  from  common 
glass  fused  with  lead  oxide,  and  rendered  opaque  by  the 
addition  of  oxide  of  tin.  Colours  may  be  produced 
by  the  addition  of  other  metallic  oxides.  Thus,  from 
copper  we  obtain  green  ;  from  iron  or  gold,  red,  and 
from  cobalt,  blue.  Small  quantities  of  manganese 
dioxide  give  us  a  fine  violet  colour  and  larger  quantities 
black.  For  the  production  of  good  colours,  the 
purity  of  the  raw  materials  is  of  the  first  importance, 
and  the  enamel  maker  looks,  therefore,  to  the  help 
of  the  chemist  to  ensure  satisfactory  results.  If  an 
enamel  is  to  be  pigmented  with  copper,  the  presence 
of  this  metal  in  the  raw  material  will  not  be  objection- 
able if  its  degree  of  oxidation  is  the  same  as  that  of  the 


76  WHAT    INDUSTRY   OWES 


pigment  used.  If  the  enamel  is  to  be  coloured  green 
with  cupric  oxide  and  that  substance  is  present  in  the 
lead  oxide  used,  the  impurity  is  of  small  consequence  ; 
but  if  the  enamel  is  to  be  coloured  yellow  with  anti- 
mony oxide,  the  green  produced  by  the  copper 
impurity  will  spoil  the  effect.  The  presence  of  small 
quantities  of  ferric  oxide  in  the  lime  will  modify  the 
green  produced  by  copper  oxide,  and  is  undesirable 
unless  it  be  required  to  tone  the  green  colour,  when 
it  can  be  added  to  materials  originally  free  from  this 
substance.  In  any  case,  the  quantity  of  impurity 
should  be  estimated  and  due  allowance  made  for 
its  effect.  Much  may  depend  on  the  method  of 
preparation  of  the  pigment.  For  instance,  cupric 
oxide  may  be  prepared  by  roasting  copper  filings  in 
air,  but  the  product  will  not  yield  nearly  such  good 
colours  as  the  oxide  chemically  prepared  from  pure 
copper  ;  and  again,  the  blue  colour  produced  from 
commercial  cobalt  compounds  is  greatly  inferior  to 
that  obtained  from  chemically  prepared  cobaltous 
silicate. 

Of  the  methods  of  preparing  chemical  and  heat  resist- 
ing enamel  for  industrial  plant  little  is  common  know- 
ledge. In  some  cases  the  coating  consists  of  two 
layers,  the  first  being  devised  to  bind  with  the  metal 
and  act  as  intermediary  between  the  metal  and  the 
finishing  enamel.  Having  in  view  the  uses  to  which 
such  vessels  are  put,  there  is  plenty  of  room  for 
further  investigation,  particularly  on  the  coefficients 
of  expansion  of  various  metals  and  alloys  and  the 
relation  of  such  physical  considerations  to  the 
composition  of  the  enamels  employed.  The  surface 
remains  good  until  a  craze  appears,  but  once  liquid 
gets  to  the  metal  the  vessel  begins  to  lose  its  coating. 
It  is  reassuring  to  know  that  chemical  firms  of  long 
standing  find  British  enamel  ware,  such  as  evaporating 
pans,  at  least  as  satisfactory  as  that  from  Germany, 
though  our  manufacturers,  as  is  often  the  case  with 
other  commodities,  have  been  less  inclined  to  put 
themselves  about  to  supply  special  requirements,  for 
instance,  with  regard  to  the  shapes  and  sizes  of  the 
vessels  required. 


TO    CHEMICAL    SCIENCE  77 


CHAPTER  XI. 
POTTERY  AND  PORCELAIN. 

THE  manufacture  of  pottery  is  yet  another  industry 
which  has  been  handed  down  from  veiy  early  times. 
Pliny  attributed  the  craft,  in  which  the  Greeks  and 
Etruscans  excelled,  to  Coraebus,  an  Athenian,  but 
obviously  it  was  of  far  greater  antiquity,  the  potter 
being  frequently  referred  to  in  ancient  Egyptian 
records  to  symbolise  the  Creator  of  man.  The 
earthenware  of  the  Greeks  and  Romans  was  unglazed 
and  porous,  but  they  rendered  their  vessels  impervious 
by  covering  them  with  wax,  tallow  and  bitumen. 
The  invention  of  porcelain  is  generally  credited  to 
the  Chinese.  It  is  mentioned  in  books  of  the  Han 
dynasty,  the  earliest  date  suggested  being  about 
185  B.C.  Its  origin  has  been  attributed  to  attempts 
made  to  imitate  glass  imported  from  Syria  and 
Egypt,  and  by  some  it  is  supposed  to  have  been 
discovered  accidentally  by  alchemists  in  their 
search  for  the  philosopher's  stone.  The  industry 
was  started  in  Japan  before  27  B.C.,  and  found 
its  way  from  the  Far  East  to  Persia,  where  it  is 
known  as  chini,  coming  to  us,  in  the  course  of  time, 
through  Arabia,  Spain,  Italy  and  Holland,  the 
potteries  of  Lambeth  being  founded  by  men  from 
Holland  about  1 640.  Porcelain  was  made  in  France,  at 
St.  Cloud,  towards  the  end  of  the  seventeenth 
century,  and  in  nearly  all  European  countries  in 
the  eighteenth  century. 

We  can  only  marvel  that  such  porcelain  as,  say, 
that  of  the  Ming  Dynasty  (1368-1643),  with  all 
the  technique  involved  in  the  selection  of  materials 
and  its  treatment,  the  craftsmanship,  colouring  and 
glazing,  was  produced  before  science,  as  we  now  use 
the  term,  had  any  voice  in  such  matters.  The 


78  WHAT    INDUSTRY   OWES 

Chinese  hard  paste  porcelain  consisted  of  kaolin 
in  a  pure  and  very  finely  divided  state,  and  petuntzo 
(finely  ground  felspathic  stone) ;  and  the  glaze  was 
made  from  selected  petuntze  mixed  with  specially- 
prepared  lime. 

One  of  the  first  European  makers  of  fine  porcelain 
of  whom  we  have  records  was  Botticher,  a  Saxon 
chemist  who  was  placed  in  charge  of  the  Meissen 
factory,  established  in  1710,  the  methods  employed 
being  kept  secret.  Pott,  a  Prussian  chemist,  en- 
deavoured to  compete  with  him,  and  although  his 
efforts  were  not  successful,  his  researches  on  materials 
likely  to  be  useful  in  porcelain  manufacture  gained 
for  the  industry  some  helpful  knowledge.  About 
the  middle  of  the  eighteenth  century  700  men  were 
employed  at  Meissen,  but  in  the  meantime  Stolzel, 
who  escaped  from  the  factory  about  1720,  founded 
the  Austrian  industry  at  Vienna,  where  500  men 
were  employed  in  1785.  Mention  should  also  be 
made  of  the  circumstance  that  William  Cookworthy, 
chemist  of  Plymouth,  to  whom  we  have  already 
referred  in  connection  with  cement,  found  kaolin 
at  Tregonning,  near  Helston,  and  took  out  a  patent 
in  1768,  which  he  worked  at  Plymouth  for  two  or 
three  years  before  establishing  a  factory  at  Bristol. 
We  must  admit  that  the  claims  of  science  so  far  were 
slender,  and  we  do  not  propose  to  pursue  the  history 
of  the  subject  further  ;  but  science  required  for  her 
own  purposes  porcelain  resistant  to  chemical  action, 
heat,  and  variations  of  temperature.  The  production 
of  Royal  Berlin  basins  and  crucibles  for  the  laboratory 
could  only  be  secured  by  careful  selection  and 
utilisation  of  the  most  suitable  materials  and  much 
painstaking  experiment.  Science  examined  the  pro- 
cesses employed  and  explained  the  changes  involved, 
while  one  notable  achievement,  viz.,  the  discovery 
of  means  for  measuring  high  temperatures,  found 
direct  application  in  the  industry.  The  temperature 
of  kilns  is  a  factor  of  no  little  importance,  and  is 
usually  determined  by  cones  made  of  oxides  of  iron, 
aluminium,  and  silicon.  The  softening  points  of 
the  cones  are  known  with  reasonable  accuracy — a 


TO    CHEMICAL    SCIENCE 


series  of  thirty-six  allowing  for  the  observation  of 
sufficient  range  of  temperature  in  porcelain  burning. 
As  the  temperatures  exceed  1000  deg.  Cent,  ordinary 
thermometric  methods  are  not  applicable.  The 
series  of  cones  could  only  be  constructed  and  stan- 
dardised with  the  aid  of  physical  science,  which  has 
provided  Le  Chatelier's  thermo-electric  pyrometer, 
Callendar's  platinum  resistance  thermometer  and  the 
Fery  radiation  pyrometer.  Their  use  in  the  stan- 
dardisation of  the  cones,  however,  is,  of  course, 
insignificant  compared  with  their  use  in  metal- 
lurgical operations. 

For  supplies  of  porcelain  for  laboratory  pur- 
poses this  country  has  hitherto  been  mainly  de- 
pendent, as  in  the  case  of  glass,  on  Germany.  Our 
chemists  have  taken  the  matter  in  hand,  however, 
and  remarkable  progress  has  been  made  by  several 
British  manufacturers.  Research  on  the  subject  of 
hard  porcelain  is  progressing,  and  there  is  good  ground 
for  hoping  that  this  branch  of  the  industry  will  be 
retained  here  in  the  future. 

The  danger  to  workers  of  lead  oxide  as  a  constituent 
of  glazes  for  earthenware  has  also  provided  a  problem 
for  chemists.  The  employment  of  lead  silicates 
instead  of  oxide,  as  suggested  by  Thorpe  and  Sim- 
monds,  is  less  harmful  ;  and  the  lead  glazes  have 
been  largely  superseded  in  recent  years  by  mixtures 
containing  silica,  alumina,  potash,  and  soda,  with 
about  10  per  cent,  of  boric  acid  to  increase  the 
fusibility.  Where  lead  is  an  essential  constituent 
it  is  applied  in  the  form  of  silicate. 


80  WHAT    INDUSTRY   OWES 


CHAPTEB  XII. 
CHEMICAL  PRODUCTS. 

IN  our  second  chapter  we  have  dealt  with  the 
heavy  chemicals  and  alkalies,  and  we  will  proceed 
now  to  consider  the  production  of  other  chemical 
substances  of  value  in  industry,  or  useful  for 
domestic,  medicinal,  scientific,  or  other  purposes. 
The  importance  of  this  branch  is  so  wide  and 
fundamental  that  it  is  not  too  much  to  say  that 
industry  as  a  whole  is  largely  dependent  on  an 
adequate  supply  of  chemical  products.  The  field 
is  so  great  that  we  cannot  attempt  to  indicate  all 
or  nearly  all  the  substances  coming  under  this  head, 
but  we  will  choose  a  few  examples  of  different  types, 
all  rendered  available  by  scientific  methods. 

Acids. — Certain  acids,  such  as  tartaric,  citric, 
lactic,  oxalic,  formic,  salicylic,  benzoic,  acetic, 
hydrofluoric,  boric,  and  arsenic  acids  are  not  prepared 
on  a  scale  comparable  with  that  of  sulphuric,  hydro- 
chloric, and  nitric,  but  their  value  in  technical 
operations  and  for  other  purposes  warrants  their 
industrial  production  in  a  condition  more  or  less 
pure,  according  to  circumstances.  Tartaric  and 
citric  acids,  from  vegetable  sources,  and  lactic  acid 
of  animal  origin,  are  used  in  calico  printing.  The 
first  is  an  ingredient  of  baking  powders  and  effer- 
vescing medicines,  such  as  seidlitz  powders,  and 
the  second  is  used  in  the  production  of  summer 
beverages.  Oxalic  acid,  -which  is  prepared  by  heating 
sawdust  with  a  mixture  of  caustic  potash  and  soda 
in  the  presence  of  air,  is  also  used  in  calico  printing, 
and  its  acid  salts  are  valuable  as  detergents,  under 
the  name  of  salts  of  sorrel  or  salts  of  lemon.  Formic 
acid  is  useful  in  dyeing  and  tanning,  and  it  is  interest- 
ing to  note  that  it  was  formerly  obtained  by  distilling 


TO    CHEMICAL    SCIENCE  81 

red  ants,  but  is  now  made  by  heating  caustic  soda 
with  carbon  monoxide  under  pressure.  Salicylic 
acid,  which  is  prepared  from  phenol,  is  used  in  the 
production  of  various  drugs,  of  which  aspirin  is  an 
example,  and  is  employed  as  an  antiseptic.  Benzoic 
acid,  from  toluene,  finds  application  in  the  manu- 
facture of  dyes  and  as  a  preservative  ;  acetic  acid 
in  bleaching,  dyeing,  and  calico  printing,  and  in 
the  manufacture  of  artificial  vinegar.  Hydrofluoric 
acid,  which  is  obtained  by  the  action  of  sulphuric 
acid  on  fluorspar,  comes  on  the  market  as  an  aqueous 
solution  in  gutta-percha  bottles,  and  is  used  for 
etching  glass  as  well  as  for  antiseptic  purposes. 
Boric  acid,  from  mineral  sources,  is  valuable  as  a 
constituent  of  various  kinds  of  glass,  and  is  used  as 
an  antiseptic  and  a  food  preservative.  Arsenic 
acid  is  employed  in  dyeing  and  in  the  preparation 
of  certain  aniline  colours. 

Bases. — Among  the  common  bases  we  have  caustic 
potash,  caustic  soda — with  which  we  have  already 
dealt — strontium  hydroxide,  and  magnesia, — alkaline 
metallic  oxides  capable  of  neutralising  acids  with  the 
production,  by  double  decomposition,  of  salts  and 
water,  the  metals  replacing  the  hydrogen  in  the 
acids.  Caustic  potash  is  prepared  either  by  electro- 
lysis of  the  chloride  or  by  the  action  of  lime  on  a- 
solution  of  potassium  carbonate,  that  salt  being 
obtained  from  the  chloride  by  a  modification  of  the 
Leblanc  process  or  by  a  method  identical  in  principle 
with  the  ammonia-soda  process,  in  which  trimethyl- 
amine — of  which  something  will  be  said  later — 
takes  the  place  of  ammonia.  For  some  purposes 
the  cheaper  base,  caustic  soda,  is  equal  in  efficiency 
to  the  more  expensive  but  more  powerful  potash ; 
but  for  others  the  latter  is  more  economical — for 
instance,  in  the  production  of  oxalic  acid  from  saw- 
dust on  the  large  scale.  When  caustic  soda  alone 
is  used,  the  yield  of  acid  is  not  more  than  a  third  of 
that  obtained  by  the  use  of  caustic  potash  or  of  a 
mixture  of  potash  and  soda.  On  the  other  hand, 
in  the  analysis  of  flue  gases,  a  valuable  check  on 
fuel  economy,  a  soda  solution  of  pyrogallic  acid  is 


82  WHAT    INDUSTRY   OWES 

a  very  much  more  rapid  and  efficient  absorbing 
reagent  for  oxygen  than  a  potash  solution  of  the 
same.  Caustic  potash  decomposes  most  metallic 
salts,  and  at  a  high  temperature  acts  with  energy 
on  many  substances.  It  is  employed  in  numerous 
industrial  operations,  and  is  ordinarily  used  for  the 
manufacture  of  soft  soap,  in  which  it  is  combined 
with  the  fatty  acids  derived  from  the  drying  oils, 
such  as  linseed,  whale,  and  seal  oils. 

Strontium  hydroxide,  prepared  mainly  from  the 
mineral  sulphate,  is  largely  used  in  the  extraction 
of  the  uncrystallisable  sugar  from  molasses.  The 
native  carbonate  requires  a  higher  temperature  for 
calcination  to  oxide  than  does  calcium  carbonate  to 
lime.  However,  in  certain  sugar  works,  where  fuel, 
including  exhausted  cane,  is  cheap,  this  process  is 
used  for  the  production  of  the  material. 

The  use  of  magnesia  in  the  ammonia-soda  process, 
and  also  as  a  refractory  material,  has  already  been 
mentioned.  Considerable  quantities  are  consumed 
in  medicine  as  an  anti-acid. 

Salts. — The  salts  of  technical  importance  are  very 
numerous.  Those  of  sodium,  on  account  of  their 
cheapness,  easy  solubility  in  water,  and  comparative 
harmlessness,  are  in  constant  use  in  many  in- 
dustries, and  are  often  interchangeable  with 
potassium  salts ;  but  in  some  cases  the  special 
properties  of  the  latter  yield  better  products  for 
manufacturing  purposes.  Potassium  permanga- 
nate and  chlorate  can  be  crystallised  better 
than  the  corresponding  sodium  salts,  and  are 
therefore  obtainable  in  a  higher  state  of  purity. 
Potassium  nitrate  is  used  in  the  manufacture  of 
ordinary  gunpowder,  whereas  the  use  of  sodium 
nitrate  would  be  impracticable  on  account  of  its 
ready  absorption  of  atmospheric  moisture.  Potassium 
sulphate,  a  constituent  of  ordinary  alum,  occurs  as 
the  mineral  kainite,  and  is  valuable  as  a  fertiliser. 
Potassium  f  errocyanide  and  bichromate  are  ingredients 
in  the  production  of  certain  pigments,  and  the  latter 
finds  employment  in  tanning  and  photography,  as 
well  as  in  the  cells  of  bichromate  electric  batteries. 


TO    CHEMICAL    SCIENCE  83 

Both  these  salts  are  now  largely  replaced  by  the 
cheaper  sodium  compounds,  owing  to  the  stoppage 
of  supplies  from  Germany.  A  mixture  of  sodium 
and  potassium  cyanides  obtained  by  heating  potassium 
ferrocyanide  with  metallic  sodium  is  used  in  the 
Mac  Arthur -Forrest  gold  extraction  process.  Sodium 
nitrite  and  hypochlorite  are  largely  used  in  the  pro- 
duction of  dyestuffs,  and,  indeed,  the  fact  that  the 
former  was  hitherto  obtained  almost  exclusively 
from  Germany  formed  no  small  obstacle  to  the 
manufacture  of  certain  important  dyes  in  this  country. 
Sodium  thiosulphate — hypo — is  used  in  bleaching 
as  an  antichlor  and  in  photography  as  a  solvent  for 
silver  halides.  Sodium  silicate — water  glass — is  used 
for  preserving  eggs  and  also  for  protecting  carbonate 
stone  buildings  from  the  action  of  weathering. 

Ammonium  sulphate  we  have  already  mentioned 
as  an  artificial  manure.  The  chloride  is  used  in 
soldering,  and  its  solution  forms  the  electrolyte  in 
Leclanche  cells.  The  nitrate  is  the  source  of  **  laugh- 
ing gas,"  and  the  commercial  carbonate  is  commonly 
the  principal  constituent  of  "  smelling  salts." 

Mention  must  also  be  made  of  certain  peroxy 
compounds,  some  of  which  have  attained  considerable 
technical  importance  in  comparatively  recent  times. 
Sodium  peroxide  is  obtained  by  the  action  of  hot  air  on 
sodium  contained  in  aluminium  trays.  The  per- 
carbonates  and  persulphates  of  sodium,  potassium, 
and  ammonium  are  prepared  by  methods  of  electro- 
lysis. Barium  peroxide  is  made  by  heating  the 
oxide  to  a  dull  redness  in  dry  air,  free  from  carbon- 
dioxide,  and  is  used  in  the  manufacture  of  hydrogen 
peroxide,  which,  as  are  other  peroxy  compounds,  is 
largely  applied  as  a  bleaching  agent  for  cellulose 
materials. 

The  salts  of  barium  and  strontium  are  very  useful 
in  pyrotechny,  the  former  for  producing  green  and 
the  latter  red  light.  Magnesium  sulphate  is  Epsom 
salts.  Mercury  salts,  including  calomel,  are  also  em- 
ployed in  medicine.  Mercuric  chloride  or  corrosive 
sublimate  is  an  excellent  antiseptic,  and  the  fulminate 
is  a  useful  explosive.  Zinc  chloride  is  used  for  the 

Q 


84  WHAT   INDUSTRY   OWES 

destruction  of  insects  and  parasites,  and  other  zinc 
compounds  are  of  medicinal  value.  Gold,  silver, 
and  platinum  salts  are  extensively  used  in  photo- 
graphy, and  copper,  tin,  and  antimony  salts  in 
dyeing  and  calico  printing.  Copper  salts  are  also 
important  in  the  Deacon  chlorine  process,  in  electro - 
typing,  in  the  manufacture  of  pigments,  and  the 
protection  of  wheat  from  smut.  Lead  carbonate, 
or  white  lead,  is  used  in  large  quantities  in  paint 
manufacture,  and  the  azide  is  an  explosive  body, 
which  may  be  employed  in  percussion  caps.  Bismuth 
and  iron  salts  find  good  use  in  medicine,  the  sulphate 
of  iron  being  also  useful  in  gold  extraction. 

Solvents. — Water,  the  commonest  and  most  useful 
solvent,  cannot  be  discussed  here  for  the  obvious 
reason  that  under  ordinary  conditions  it  is  not  a 
chemical  product  from  our  point  of  view.  Water 
purified  by  distillation,  however,  is  a  commercial 
article,  and  might  perhaps  be  included.  Among 
inorganic  solvents,  mention  must  be  made  of  ammo- 
niacal  copper  solution  for  cellulose,  and  sulphur 
chloride,  which  is  prepared  by  the  direct  union  of 
the  elements  and  is  a  valuable  solvent  for  sulphur, 
being  largely  employed  in  vulcanising  rubber.  The 
common  acids,  such  as  nitric,  sulphuric,  and  hydro- 
chloric, are  excellent  solvents  for  metals  and  oxides, 
but  the  solutions  so  obtained  are  not  simple,  the 
original  metal  or  oxide  not  being  recoverable  by 
merely  evaporating  the  solvent.  Alcohol,  or  spirits 
of  wine,  prepared  by  the  rectification  of  fermented 
liquor,  is  a  valuable  solvent  in  many  ways,  such  as, 
for  instance,  the  purification  of  certain  organic  pro- 
ducts by  crystallisation  from  alcoholic  solution. 

In  manufacturing  processes,  substances,  such  as 
fatty  oils,  rubber,  and  sulphur,  which  are  insoluble 
in  water,  are  frequently  required  in  the  form 
of  a  solution,  and  it  rests  with  the  chemist  to 
discover  the  best  solvents  for  such  substances  and 
the  methods  of  preparing  and  applying  them. 
Carbon  disulphide,  a  volatile,  poisonous,  highly 
refracting  liquid,  heavier  than  water,  was  discovered 
in  1796  by  Lampadius,  who  obtained  it  by  distilling 


TO    CHEMICAL    SCIENCE  85 

iron  pyrites  with  carbon.  As  ordinarily  met  with 
it  has  a  most  obnoxious  smell,  but  when  pure  the 
odour  is  ethereal  and  not  unpleasant.  It  occurs 
in  the  products  of  the  destructive  distillation  of  coal, 
but  is  manufactured  mainly  by  the  direct  union  of 
charcoal  or  coke  with  sulphur  in  retorts  or  in  the 
electric  furnace.  Its  uses  are  many  ;  it  dissolves 
sulphur,  gums,  rubber,  phosphorus,  resins,  essential 
oils,  iodine,  and  alkaloids.  It  is  used  sometimes  for 
the  extraction  of  fatty  oils  remaining  in  the  residue 
after  crushing  seeds,  being  subsequently  removed  by 
distillation  and  used  again.  A  solution  of  sulphur 
in  carbon  disulphide  is  used  for  the  vulcanisa- 
tion of  rubber.  Its  poisonous  action  has  been 
utilised  for  destroying  blight  in  grain  without  ill 
effects — except  to  the  blight ;  and  potassium  thio- 
carbonate — a  compound  of  carbon  bisulphide  and 
potassium  sulphide — is  destructive  to  insects  which 
infest  vines.  On  account  of  its  high  index  of  refrac' 
tion,  hollow  glass  prisms  filled  with  carbon  disulphide 
are  employed  in  spectroscopy.  A  solution  of  iodine 
in  carbon  disulphide  is  of  use  in  certain  physical 
experiments,  for  the  reason  that  such  a  solution  is 
opaque  to  rays  of  light,  while  it  transmits  heat  rays 
freely.  Lastly,  we  may  mention  that  from  carbon 
disulphide  and  chlorine  is  obtained  carbon  tetra- 
chloride,  a  solvent  for  fats,  which  is  also  employed 
in  the  production  of  certain  dyes,  and  being  non- 
inflammable,  serves  a  useful  purpose  in  fire -extinguish- 
ing apparatus. 

Among  the  organic  solvents  are  several  that  are  also 
anaesthetics.  Chloroform  was  discovered  simultane- 
ously by  Guthrie,  an  American,  and  Souberain,  a 
Frenchman,  in  1831,  and  was  first  employed  as  an  anae- 
sthetic by  Lawrence  in  London,  and  Simpson  in  Edin- 
burgh, in  1847.  Itis  prepared  on  the  large  scale  by  the 
action  of  chloride  of  lime  on  alcohol  or  acetone,  the 
product  being  a  valuable  solvent  for  fatty  oils,  india- 
rubber,  alkaloids,  resins,  and  other  substances. 
Prepared  by  the  above  process,  however,  it  contains 
highly  poisonous  impurities,  which  are  gravely 
detrimental  to  its  use  as  an  anaesthetic,  for  which 

G  2 


86  WHAT    INDUSTRY    OWES 


purpose  it  is  obtained  by  distilling  chloral — resulting 
from  the  action  of  chlorine  on  alcohol — or  its  hydrate 
with  caustic  soda,  the  final  product  being  sufficiently 
pure. 

Ether,  another  solvent,  also  an  anaesthetic,  was 
known  in  the  sixteenth  century,  and  described  by 
Valerius  Cordus,  a  German  physician.  It  was 
prepared  by  the  action  of  sulphuric  acid  on  alcohol, 
and  in  the  early  part  of  the  eighteenth  century  was 
employed  as  a  mixture  with  alcohol,  under  the 
name  of  Hoffmann's  Anodyne,  to  allay  pain.  Its 
use  as  an  anaesthetic  was  discovered  by  Charles 
Jackson,  of  Boston,  in  1842.  The  most  economical 
method  of  manufacture  is  the  continuous  process, 
devised  by  Boullay. 

Acetone,  a  valuable  solvent  for  oils,  and  employed 
largely  in  the  manufacture  of  explosives,  is  found 
in  the  free  state  in  the  products  of  the  destructive 
distillation  of  wood,  and  is  obtained  by  the  dry 
distillation  of  acetate  of  lime,  which  substance  is 
also  produced  from  pyroligneous  acid. 

Fine  Chemicals. — The  many  substances  we  have 
mentioned  under  the  heading  of  chemical  products, 
represent  only  a  very  small  proportion  of  those  in 
common  use,  and  do  not  include  all  that  are  employed 
in  the  laboratory,  or  those  at  present  of  purely 
scientific  interest,  which  are  very  numerous.  We  say 
"  at  present  "  purposely,  for  no  one  can  tell  how  soon 
they  may  find  practical  application.  The  value  of 
"  research  for  its  own  sake  "  has  already  been  shown 
in  the  many  examples  we  have  cited  of  the  discovery 
of  elements  and  compounds,  at  first  merely  regarded 
a,s  scientific  curiosities,  but  sooner  or  later  proved  to 
be  of  incalculable  importance  to  industry  and  to  the 
world.  So  much  depends  on  the  accuracy  of 
analytical  results,  that  an  adequate  supply  of 
chemicals  in  a  sufficiently  pure  state  to  be  used  as 
reagents  is  an  essential  requirement  in  all  laboratories. 
The  statement  should  be  too  obvious  to  mention,  but 
it  must  be  remembered  that  we  buy  and  sell  on 
analytical  data  ;  we  check  and  control  vast  technical 
operations  on  such  data,  and  must  be  able  to  rely  on 


TO    CHEMICAL    SCIENCE  37 

sound  reagents  in  most  chemical  investigations. 
German  fine  chemicals  have  enjoyed  a  reputation  for 
purity,  but  of  chemicals  generally,  apart  from  dye- 
stuffs,  we  produce  the  bulk  of  our  own  requirements  ; 
our  export  trade  has  been  greater  than  that  of  our 
continental  competitors,  and  there  is  no  doubt  that, 
with  increased  scientific  control  and  care,  we  can 
manufacture  products  of  equally  high  standard. 

A  number  of  concerns  of  established  repute  are  now 
energetically  developing  the  fine  chemical  industry. 
The  processes  of  manufacture  and  purification  call 
for  the  services  of  highly  trained  chemists,  of  whom 
the  supply  will  certainly  be  forthcoming  as  the  demand 
for  them  increases. 

A  pamphlet  prepared  by  a  special  committee 
appointed  by  the  Councils  of  the  Institute  of 
Chemistry  and  of  the  Society  of  Public  Analysts,  was 
issued  early  in  1915,  giving  details  of  the  tests  for 
purity  of  a  number  of  important  analytical  reagents. 
This  provides  a  standard  for  the  manufacturers  who 
will  still  continue  to  make  products  of  other  grades 
for  various  uses,  while  producing  the  fine  chemicals 
up  to  the  specification  standard  at  a  higher  cost, 
which  the  consumer  is  always  willing  to  pay.  For 
one  example  out  of  many,  sulphuric  acid  for  many 
technical  purposes  is  highly  impure.  In  some  cases 
the  impurities  are  substances  which  do  not  affect  the 
behaviour  of  the  acid  and  its  suitability  for  the  purposes 
for  which  it  is  required.  A  purer  acid  is  made  for 
general  laboratory  use  ;  but  for  good  analytical  work 
the  acid  must  be  free  from  lead,  calcium  and  other 
metals,  from  arsenic,  selenium,  nitrogen  and  halogen 
•ompounds,  and  from  reducing  substances,  and  should 
leave  no  solid  residue  on  evaporation  to  dryness. 
Tests  are  prescribed  whereby  such  impurities  may 
be  detected,  but  it  is  most  advantageous  to  be  able 
to  secure  reliable  supplies  without  the  necessity  of 
applying  them,  and  possibly  being  obliged  to  purify 
the  substances  in  the  laboratory  before  using  them. 
The  purification  of  sulphuric  acid  on  the  small  scale 
is  an  expensive,  difficult,  and  tedious  operation.  It 
is  a  hopeful  sign  therefore  that  a  number  of  our  well- 


88  WHAT    INDUSTRY   OWES 

known  manufacturers  are  now  producing  guaranteed 
analytical  reagents  of  recognised  standard  degrees 
of  purity. 

Drugs. — After  all  the  references  we  have  made  to 
the  work  of  the  chemist  in  industry,  we  do  not  need 
to  labour  the  distinction  between  the  man  who 
practises  chemistry  and  the  man  who  practises 
pharmacy.  The  latter  has  to  depend  on  the  former 
for  many  of  the  materials  he  employs  in  dispensing, 
or  the  physician  may  prescribe  with  very  uncertain 
results,  and  the  patient  perish,  or,  in  any  case,  pay  to 
no  purpose.  The  subject  of  drugs  and  pharma- 
ceuticals,  with  all  its  ramifications  into  the  substances 
compounded  into  medicines  of  all  kinds,  pills,  powders, 
ointments,  lotions,  tinctures,  and  so  forth,  is  too 
extensive  for  us  to  treat  adequately,  and  we  can  only 
deal  with  the  subject  by  indicating  a  few  develop- 
ments in  this  important  branch  of  industry. 

Many  of  the  drugs  used  in  medicine  are  of  vegetable 
origin.  Quinine,  for  instance — discovered  in  1820  by 
Pelletier  and  Caventou — is  extracted  from  the  bark 
of  trees  of  the  Cinchona  species.  Strychnine  is 
obtained  from  the  seeds  of  various  plants  such  as 
Strychnos  mix  vomica.  Atropine  is  prepared  from 
deadly  nightshade  juice,  which  contains  two  alkaloids, 
hyoscyamine  and  hyoscine.  The  juice  is  treated  with 
caustic  potash,  the  hyoscyamine  being  thereby  con- 
verted into  atropine.  The  mixture  is  shaken  with 
chloroform  and  the  solvent  evaporated,  the  atropine 
being  extracted  with  dilute  sulphuric  acid,  precipi- 
tated by  potassium  carbonate,  and  re-crystallised  from 
alcohol.  A  solution  of  the  alkaloid  has  the  property, 
when  placed  in  the  eye,  of  dilating  the  pupil,  a  most 
useful  aid  to  the  ophthalmic  surgeon. 

An  increasing  number  of  useful  organic  drugs, 
including  alkaloids,  is  now  made  synthetically  from 
other  chemical  substances.  Many  of  these  are 
unknown  in  Nature,  their  production  and  utilisation 
being  solely  due  to  science.  Salicylic  acid  and  its 
derivatives,  including  aspirin,  are  made  from  phenol, 
and  used  extensively  in  the  treatment  of  rheumatic 
and  nervous  disorders.  On  account  of  certain  objec- 


TO    CHEMICAL    SCIENCE  89 

tionable  physiological  properties,  attempts  have  been, 
and  are  being,  made  to  obtain  other  derivatives  that 
have  no  such  disadvantages,  and  good  results  have 
been  obtained  with  acetylsahcylic  anhydride  and 
cinnamoylsalicylic  anhydride.  The  antipyretics, 
phenacetin  and  antifebrin,  are  made  from  phenol; 
antipyrene,  which  is  put  to  similar  uses,  being  the 
product  obtained  by  methylating  the  pyrazolon 
derivative  formed  by  the  condensation  of  acetoacetic 
ester  with  phenylhydrazine.  Derivatives  of  antipyrene 
include  salipyrene  and  tolypyrene.  Veronal  is 
another  synthetic  drug. 

The  use  of  metallic  compounds,  as  bactericidal 
agents,  has  long  been  known.  Compounds  of  mercury 
have  long  been  used  in  the  treatment  of  certain  dis- 
eases. Recently  the  researches  of  Ehrlich  on  the 
organic  compounds  of  arsenic  have  done  much  to 
alleviate  suffering,  such  complex  bodies  being  much 
less  poisonous  to  human  beings  than  are  the  simpler 
compounds  of  arsenic.  Salvarsan  and  neosalvarsan 
have  met  with  success.  One  of  the  simplest  of  such 
derivatives,  atoxyl,  has  been  used  in  the  treatment  of 
sleeping  sickness. 

Local  anaesthetics,  administered  hypodermically, 
include  cocaine,  novacaine,  and  stoveine,  the  first 
being  extracted  from  the  coca  plant  by  alcohol  acidi- 
fied with  a  small  quantity  of  sulphuric  acid,  and  the 
two  latter  being  synthetic  products. 

Among  antiseptics  we  must  again  mention  phenol 
(now  being  manufactured  from  benzene  in  large  quan- 
tities for  making  explosives),  cresols,  formaldehyde, 
mercuric  chloride — corrosive  sublimate — and  boric 
acid  ;  while  as  disinfectants  and  insecticides,  bleaching 
powder,  carbolic  acid,  potassium  permanganate, 
naphthalene,  and  zinc  chloride — all  chemical  products 
— are  now  largely  used. 


90  WHAT    INDUSTRY   OWES 


CHAPTER  XIII. 
PHOTOGRAPHY. 

THIS  beautiful  and  now  almost  essential  art  is 
dependent  upon  the  action  of  light  on  various 
chemical  compounds,  principally  the  salts  of  silver. 
It  was  first  observed  by  Boyle  about  the  middle  of 
the  seventeenth  century,  that  luna  cornea — silver 
chloride — darkens  on  exposure  to  light,  and  this 
phenomenon  was  further  investigated  by  the  Swedish 
chemist,  Scheele,  in  1784.  No  attempt,  however, 
was  made  to  utilise  this  property  for  the  production 
of  pictures  until  1802,  when  Thomas  Wedgwood 
obtained  prints  of  leaves  and  other  flat  bodies  on 
sensitive  surfaces  prepared  by  moistening  white 
leather  or  paper  with  silver  nitrate  solution.  Similar 
experiments  were  carried  out  by  Sir  Humphry  Davy, 
but  the  pictures  produced  lacked  one  important 
advantage  ;  they  were  not  permanent  in  daylight,  and 
therefore  had  to  be  kept  in  the  dark  and  examined 
only  in  weak,  artificial  light.  The  next  workers  of 
note  were  Niepce  and  Daguerre,  a  great  advance 
being  made  by  the  latter,  when,  in  1839,  he  introduced 
a  new  departure,  well-known  as  the  daguerrotyp© 
process.  This  was  long  ago  superseded  by  other  and 
better  methods,  but  it  served  the  purpose  of  indicating 
the  right  road  to  success.  A  plate  of  polished  silver 
was  exposed  to  the  action  of  iodine  vapour,  being 
thereby  covered  with  a  film  of  silver  iodide.  On 
exposure  in  a  camera  no  apparent  change  took  place 
until  development,  as  is  the  case  with  modern 
photographic  plates.  The  method  of  development 
of  the  Daguerre  plates  was  an  accidental  discovery. 
Daguerre,  while  experimenting,  was  called  away  just 
after  he  had  removed  a  plate  from  his  camera.  For 
safety,  he  put  the  plate  in  the  first  dark  place  that 


TO    CHEMICAL    SCIENCE  91 

caught  his  eye — a  box  containing  odd  pieces  of 
apparatus — and  when  he  returned  to  continue  the 
work,  he  was  surprised  to  find  that  during  his  absence 
the  image  on  the  plate  had  developed.  Investiga- 
tion of  the  contents  of  the  box  led  to  the  final  con- 
clusion that  the  agent  was  some  metallic  mercury 
loose  in  the  bottom  of  the  box.  This  provided  the 
means  of  development,  the  plates  after  exposure  to 
light  being  acted  upon  by  the  vapour  of  mercury. 
The  image  was  made  permanent  by  dissolving  the 
unaltered  silver  iodide  in  the  parts  less  affected  by 
light  with  a  hot  solution  of  common  salt,  an  improve- 
ment being  almost  immediately  effected  by  the 
suggestion  of  Herschel,  that  sodium  thiosulphate — 
"  hypo  " — was  a  more  suitable  fixing  agent. 

Meanwhile,  other  investigators  had  not  been  idle. 
In  the  Calotype  or  Talbotype  process,  elaborated  by 
Fox  Talbot,  and  introduced  in  1841,  we  find  the 
principle  of  modern  photography  showing  signs  of 
active  germination.  The  method  depended  entirely 
on  the  use  of  papers  sensitised  with  chloride  and 
iodide  of  silver.  In  his  earlier  researches,  a  piece  of 
paper  was  covered  with  silver  chloride  by  immersion, 
successively  in  solutions  of  common  salt  and  silver 
nitrate.  Prolonged  exposure  in  the  camera  resulted 
in  the  production  of  a  negative  image,  which  could  be 
fixed  by  common  salt  solution.  This  method  wa» 
soon  afterwards  greatly  modified  in  the  following  way. 
The  image  formed  by  the  camera  lens  was  received 
on  a  sheet  of  paper  covered  with  silver  iodide,  and  was 
subsequently  developed  by  a  mixture  of  silver  nitrate, 
acetic  acid,  and  gallie  acid.  When  the  resulting 
negative  was  made  transparent  by  means  of  wax, 
positive  prints  could  be  obtained  by  allowing  sunlight 
to  pass  through  the  negative  on  to  a  piece  of  the  sensi- 
tive silver  cKloride  paper.  The  first  use  of  glass 
plates  was  made  by  Archer  in  1851,  the  glass  being 
covered  with  a  film  of  collodion  in  which  cadmium 
or  zinc  bromide  or  iodide  had  been  dissolved.  The 
plate  was  sensitised  by  dipping  into  a  solution  of 
silver  nitrate  and  it  was  exposed  in  the  wet  state  in  the 
camera,  the  image  being  developed  by  washing  with 


92  WHAT    INDUSTRY   OWES 

some  reducing  agent,  such  as  ferrous  sulphate.  The 
image  being  fixed  by  a  solution  of  sodium  thiosulphate 
or  potassium  cyanide  provided,  when  dried,  a  negative 
from  which  any  number  of  positive  prints  could  be 
taken.  By  this  means  the  detail  of  the  pictures  was 
better  than  that  given  by  the  older  processes,  and  other 
advantages  were  obtained,  including  the  shortened 
time  of  exposure  of  the  more  sensitive  collodion  film. 
By  this  time  very  many  workers  had  entered  the 
field,  and  the  art  made  rapid  strides.  A  further 
improvement  was  the  introduction  of  dry  plates,  the 
sensitive  surface  being  composed  of  gelatine  impreg- 
nated with  silver  bromide ;  but  to  give  a  detailed 
history  of  the  development  of  modern  photography 
would  be  beyond  the  scope  of  this  article. 

The  modern  dry  plates  consist  of  sheets  of  glasa 
cut  to  standard  size  and  covered  with  a  gelatine 
emulsion  of  silver  bromide.  The  emulsion  is  prepared 
by  the  inter-action  of  ammoniacal  silver  nitrate  with 
excess  of  potassium  bromide  containing  a  little  iodide 
in  hot  gelatine  solution,  the  emulsion,  formed  being 
kept  at  a  temperature  of  45  deg.  Cent,  for  some  time — 
an  operation  which  increases  the  sensitiveness.  The 
emulsion  is  then  washed  free  from  soluble  salts,  run 
in  an  even  coating  on  to  the  plates,  and  dried.  After 
exposure,  the  plates  are  developed  by  the  reducing 
action  of  certain  compounds,  such  as  pyrogallic  acid, 
hydroquinone,  metol,  ferrous  oxalate,  and  others,  with 
various  substances  added  to  modify  favourably  the 
course  of  development.  The  developed  plates  are 
fixed  by  means  of  a  solution  of  sodium  thiosulphate, 
well  washed  and  dried.  The  introduction  of  celluloid 
films  has  lessened  the  inconvenience  attached  to  the 
bulkiness  and  rigidity  of  plates,  films  being  invariably 
used  when  compactness  and  lightness  of  outfit  are 
required. 

Many  kinds  of  printing  paper  are  available  at 
the  present  time.  Silver  chloride  papers,  both 
in  gelatine  and  collodion,  are  used  for  daylight 
printing,  ordinary  P.O. P.  being  toned  with  a  solution 
containing  gold  chloride  before  fixing  with  hypo. 
Self-toning  papers  require  washing  and  fixing  only, 


TO    CHEMICAL    SCIENCE  93 

the  paper  already  containing  the  necessary  gold,  but 
modifications  of  tone  may  be  obtained  by  washing 
the  prints  in  a  solution  of  common  salt  before  fixing. 
Silver  bromide  and  silver  iodide  are  the  sensitive 
bodies  in  bromide  and  gaslight  papers,  of  which  many 
varieties  are  on  the  market,  these  papers  requiring 
development,  as  in  the  case  of  plates.  Beautiful 
tones  may  be  obtained  by  platinotype  papers. 

Other  methods  of  printing  include  the  carbon 
process,  depending  upon  the  fact  that  when  a  gelatine 
solution  of  potassium  bichromate  is  exposed  to  light, 
the  gelatine  becomes  insoluble  in  water.  Brilliant 
black  and  white  prints  may  be  obtained  by  the 
adhesion,  after  washing,  of  finely  divided  carbon  to 
the  insoluble  gelatine  surface.  The  paper  for  the 
blue  prints  familiar  to  engineers  is  prepared  by  immer- 
sion in  a  solution  containing  potassium  ferrocyanide 
and  ferrous  ammonium  citrate,  the  prints  merely 
requiring  to  be  washed  in  water  and  dried.  Other 
methods  have  been  devised  to  obtain  engineers' 
prints  in  various  colours  on  a  white  ground,  but  for 
most  purposes  the  blue  print  method  is  adequate. 

Colour  photography,  which  has  attracted  much 
attention  during  the  last  few  years,  has  been  developed 
with  some  success.  Many  processes  have  been 
devised,  one  of  the  most  striking  being  the  mirror 
method  of  Lippmann,  which  depends  upon  the 
interference  of  direct  and  reflected  rays  at  different 
depths  in  the  film,  the  ultimate  deposition  of  metallic 
silver  produced  by  development  occurring  at  a  distance 
from  the  reflecting  surface  fixed  by  the  wave  length 
of  the  impinging  light.  On  viewing  the  developed 
and  fixed  plate  similar  interference  phenomena  take 
place  with  the  consequent  natural  colouring  of  the 
image.  With  the  aid  of  orthochromatic  and  of  pan- 
chromatic plates,  prepared  by  the  use  of  various 
dyes,  combined  with  screens  or  colour  filters,  excellent 
coloured  photographs  may  be  obtained.  Three - 
plate  and  single-plate  processes  are  available,  the 
latter  type  being  more  convenient.  The  Lumiere 
process  is  a  single-plate  process,  in  which  the  screen 
consists  of  a  mixture  of  starch  grains,  dyed  red, 


WHAT    INDUSTRY    OWES 


green,  and  blue,  incorporated  in  a  single  layer  in  the 
plate.  All  these  colour  photography  processes, 
however,  are  still  somewhat  expensive. 

Mention  could  be  made  of  many  debts  to  photo- 
graphy, including  the  discovery  of  radioactivity, 
which  was  directly  due  to  the  sensitiveness  of  the 
photographic  plate,  the  discovery  of  stars  too  faint 
to  be  observed  by  the  most  powerful  telescopes,  the 
invention  of  photo  -mechanical  processes  employed  in 
illustrating  books  and  journals,  photomicrography  and 
its  numerous  applications,  and  the  cinematograph, 
Apart  from  its  everyday  uses  in  peace  and  war. 

Photographic  Materials.  —  The  manufacture  of 
photographic  materials  is  essentially  a  branch  of  the 
fine  chemical  industry,  since  the  production  of  good 
results  depends  as  much  on  the  purity  of  the  materials 
employed  as  on  the  manner  of  employing  them. 
Developers,  such  as  pyrogallic  acid,  metol,  and  hydro  - 
quinone,  toning  solutions  containing  gold  chloride, 
and  the  materials  for  making  and  sensitising  plates, 
films,  and  printing  papers  must  necessarily  be  pure. 
In  fact,  the  whole  art  of  photography  depends,  from 
start  to  finish,  on  a  high  order  of  scientific  work,  both 
chemical  and  physical. 


TO    CHEMICAL    SCIENCE  95 


.CHAPTER  XIV. 
AGRICULTURE  AND  FOOD. 

AGRICULTURE. 

AGRICULTURE,  though  primarily  concerned  with  the 
cultivation  of  the  soil — tillage,  pasturage,  and 
gardening — may  be  regarded  as  the  industry  to 
which  we  look,  not  only  for  food — animal  and 
vegetable — but,  directly  or  indirectly,  for  clothing 
and  textiles,  timber,  drugs,  leather,  rubber,  and  a  host 
of  other  necessaries  and  comforts.  Little  reflection 
is  required  to  show  that  agriculture  is  dependent  on 
science,  and,  although  many  practical  farmers 
still  scout  such  ideas,  the  various  branches  of  the 
industry  owe  much  to  geology,  biology — botany  and 
zoology — chemistry,  physics  and  meteorology,  as  well 
as  to  the  art  of  engineering.  We  propose  to  refer, 
briefly,  to  the  work  of  the  chemist,  especially  in 
connection  with  the  subject  of  fertilisers. 

The  fear  has  been  expressed  from  time  to  time  that, 
even  making  allowance  for  the  effects  of  war,  the  pro- 
duction of  food  will  fall  behind  the  needs  of  the 
increasing  population  of  the  earth,  unless  science  can 
devise  measures  for  coping  with  the  problem.  We 
have  shown  how,  through  science,  fields  devoted  to 
the  cultivation  of  indigo  and  madder  have  made  way 
for  cereals,  and  we  may  confidently  expect  further 
changes  of  the  same  kind,  or  even  find,  in  the  labora- 
tory, means  for  obtaining  food  independently  of  the 
processes  of  Nature  by  reproducing  something  akin 
to  the  vital  processes  of  vegetable  and  animal  life. 

Fertilisers. — Mother  Earth  readily  repays  the  kindly 
attentions  of  man  and  offers  an  illimitable  field  to 
science  in  the  development  of  food  supplies  for  man 
and  beast.  The  chemist  examines  the  soil,  decides 
the  means  to  be  adopted  for  the  restoration  of  its 


96  WHAT    INDUSTRY   OWES 

fertility,  and  barren  land  is  thereby  reclaimed. 
Natural  manures,  through  the  agency  of  which  the 
soil  regains  its  creative  energy,  are  supplemented  by 
artificial  fertilisers,  and  the  yield  of  foodstuffs  is 
increased.  Thus,  sodium  nitrate,  found  in  enormous 
deposits  in  certain  parts  of  Western  South  America,  is 
very  largely  used  as  a  nitrogenous  manure,  the  crude 
material  being  purified  by  crystallisation.  Potassium 
sulphate,  in  the  form  of  the  mineral  kierserite, 
enriches  the  soil  deficient  in  potash.  Ammonium 
sulphate,  from  the  distillation  of  coal  and  shale,  is 
another  valuable  nitrogenous  manure,  and  super- 
phosphate of  lime,  prepared  by  the  action  of  sulphuric 
acid  on  mineral  phosphates,  provides  a  fertiliser 
containing  a  large  proportion  of  soluble  phosphate. 
The  manufacture  of  this  substance,  moreover,  has 
been  largely  instrumental  in  keeping  alive  the  lead 
chamber  process — chamber  acid,  as  such,  being  suit- 
able for  the  purpose. 

The  calculation  of  Vergara  that  the  South  American 
sodium  nitrate  beds  would  be  exhausted  by  the 
year  1923  has  been  proved  to  be  erroneous.  Surveys 
of  the  known  beds  show  that  the  supply  from  them 
will  be  sufficient  to  meet  the  increasing  demand  for 
the  next  fifty  years  or  more,  while  the  general  character 
of  the  country  leads  to  the  reasonable  supposition 
that  other  beds  of  vast  extent  exist  and  will  be 
capable  of  supplying  the  needs  of  the  world  for  a 
further  200  years.  However,  the  end  must  come 
sooner  or  later,  and  in  view  of  the  importance  of  this 
substance,  both  as  a  fertiliser  and  as  a  starting 
material  in  the  manufacture  of  potassium  nitrate, 
nitric  acid,  and  other  nitrogen  compounds,  the 
prospective  shortage  has  given  an  impetus  to  research 
with  the  object  of  utilising  the  nitrogen  in  the  air. 
One  of  the  methods  employed  aims  at  the  preparation 
of  nitrates  by  heating  air  in  a  specially  constructed 
electric  furnace  in  which,  by  a  suitable  arrangement 
of  electro -magnets,  the  arc  is  caused  to  assume  a 
discous  shape.  The  oxide  of  nitrogen  produced  is 
led  away  to  an  oxidising  chamber,  where  it  is  converted 
by  atmospheric  oxygen  into  a  higher  oxide,  which  is 


TO    CHEMICAL    SCIENCE  97 

absorbed  by  bases  such  as  lime,  soda,  potash,  or 
ammonia.  The  process,  primarily  discovered  by  Sir 
William  Crookes,  was  adapted  by  McDougall  and 
Howies,  in  America,  and  later  by  Birkeland  and  Eyde, 
in  Norway,  where  electric  power  is  cheap,  and  bases, 
manufactured  in  Germany,  were  sent  to  Norway  and 
returned  as  nitrates. 

The  cyanamide  process,  which  forms  a  great 
German  industry,  consists  in  heating  calcium  carbide 
with  nitrogen  in  the  electric  furnace.  The  nitrogen 
is  obtained  from  liquid  air  by  boiling  off  the  oxygen, 
or  as  residue  from  water  gas  or  producer  gas,  which 
has  been  used  in  the  manufacture  of  hydrogen.  The 
cyanamide  is  applied  directly  as  a  manure,  and  on 
exposure  to  water  at  ordinary  temperature  slowly 
evolves  ammonia,  which,  under  the  action  of  nitrifying 
bacteria,  is  converted  into  compounds  of  nitrogen 
readily  absorbed  by  the  plant.  It  may  be  noted  also 
that  ammonia  is  easily  formed  by  heating  calcium 
cyanamide  with  water  under  pressure.  If  barium 
carbide  is  used  instead  of  the  calcium  compound,  the 
main  yield  is  barium  cyanide,  a  convenient  starting 
material  for  the  manufacture  of  other  cyanides. 

Nitrides,  such  as  those  of  magnesium,  boron,  and 
silicon,  are  prepared  in  the  electric  furnace,  and  find 
application  as  manures  rich  in  nitrogen  and  as  sources 
of  ammonia,  though  their  cost  of  production  is  rather 
high.  Many  other  processes  have  been  patented  and 
used  for  the  fixation  of  nitrogen,  and  British  chemists 
have  not  been  idle,  in  spite  of  the  difficulty  of  com- 
peting against  the  lower  cost  of  power  in  other 
countries.  Water  power,  abundant  in  Norway,  is 
readily  converted  into  electricity,  and  is,  therefore, 
a  most  valuable  possession  in  this  connection  ;  but 
we  are  assured  that  an  earnest  endeavour  is  being 
made  to  produce  nitrates  in  this  country  at  the  present 
time.  Incidentally,  we  would  remark  that  the 
fixation  of  nitrogen  is  of  such  importance  that  it  is 
practically  certain  that  if  Germany  had  not  solved 
the  problem  before  the  war,  she  could  not  have 
maintained  for  so  long  the  supply  of  munitions  to  her 
army. 


98  WHAT    INDUSTRY    OWES 

Basic  slag — the  phosphatic  slag  from  the  Thomas 
and  Gilchrist  basic  Bessemer  process — when  finely 
ground  is  a  useful  manure  for  certain  purposes,  grass 
land  especially  deriving  benefit  from  its  application. 
Its  employment  in  other  directions  has  not,  so  far, 
been  extensive,  possibly  owing  to  the  existence  of  a 
somewhat  arbitrary  standard  of  valuation.  It  is 
desirable  that  careful  experiment  should  be  made 
with  various  crops  to  ascertain  if  this  standard  is 
reasonable  for  all  purposes.  In  the  result  it  is  not 
unlikely  that  great  dumps  of  slag,  hitherto  regarded 
as  waste,  both  from  the  basic  Bessemer  and  from  the 
open-hearth  processes,  may  be  available  for  agri- 
cultural purposes. 

The  quality  of  artificial  fertilisers  is  to  some  extent 
safeguarded  by  the  provisions  of  the  Fertilisers  and 
Feeding  Stuffs  Act,  under  which  the  seller  of  any 
artificially  prepared  or  imported  fertiliser,  and  any 
artificially  prepared  feeding  stuff,  is  required  to  give  a 
warranty  to  the  purchaser  as  to  the  constituents  of 
value  in  these  articles,  and  an  undertaking  that  the  per- 
centages found  in  these  articles  do  not  differ  from  those 
stated  in  the  invoice,  beyond  certa.in  prescribed  limits 
of  error.  Official  agricultural  analysts  and  samplers 
are  appointed  to  assist  in  the  administration  of  the 
Act,  and  the  Board  of  Agriculture  is  empowered  to 
make  regulations  for  the  purpose  of  carrying  the  Act 
into  execution.  It  is  generally  agreed,  however,  that, 
with  few  exceptions,  the  county  and  borough  authori- 
ties concerned  have  practically  ignored  it,  and  beyond 
appointing  officials  as  required  by  the  Act  have  given 
them  little  or  nothing  to  do,  so  that  offending  traders 
are  rarely  brought  to  justice. 

Feeding  Stuffs. — Among  the  principal  artificially 
prepared  feeding  stuffs  for  cattle  and  sheep  may  be 
mentioned  cotton  cake  and  meal,  which  are  very  rich 
in  albuminoids,  as  are  also  cake  and  meal  from  the 
ground  nut  and  Chinese  soya  bean,  and  linseed  and  rape 
cake,  prepared  from  the  marc  or  refuse  from  crushing 
for  oil.  Other  industries  provide  food  material,  such 
as  brewers'  grains,  malt  dust  and  yeast,  and  beet 
sugar  fibrous  wastes. 


TO    CHEMICAL    SCIENCE  99 


FOOD. 

While,  as  we  have  indicated  above,  the  measures 
taken  to  assure  the  quality  of  food  for  cattle  are,  to 
a  large  extent,  ineffective,  those  taken  in  respect  of 
our  own  food  are  certainly  more  satisfactory,  although 
the  Sale  of  Food  and  Drugs  Acts  might,  with  advan- 
tage, be  more  thoroughly  administered  in  some  parts 
of  the  country.  The  term  "  food  "  includes  every 
article  used  for  food  or  drink  by  man,  other  than 
drugs  or  water,  and  any  article  which  ordinarily 
enters  into,  or  is  used  in,  the  composition  or  prepara- 
tion of  human  food,  and  also  flavouring  matters  and 
condiments  ;  the  term  "  drug "  includes  medicines 
for  internal  or  external  use.  Public  analysts  are 
appointed  to  examine  samples — chiefly  milk  and 
dairy  products — taken  under  the  Act,  and  proceedings 
frequently  follow  both  in  the  interests  of  health  and  of 
the  prevention  of  fraud.  Some  may  protest  that  the 
work  of  the  public  analyst  is  not  in  the  interests  of 
industry,  but  it  must  be  admitted  that  the  honest 
vendor  is  directly  protected  by  the  prosecution  of  the 
fraudulent,  and  it  should  be  noted  also  that  many 
prepared  foods,  such  as  biscuits,  cocoa,  margarine, 
preserved  meat,  fish,  fruits  and  vegetables,  jams  and 
confectionery,  and  beverages  are  produced  under 
scientific  supervision. 

The  methods  of  preservation  of  perishable  food 
products  are  due  to  the  application  of  science.  The 
sterilisation  by  boiling  of  meat  and  of  fish,  followed 
by  immediate  hermetic  sealing  in  cans,  is  the  result 
of  a  knowledge  of  the  nature  of  bacterial  life,  as  also 
is  the  practice  of  preserving  by  the  application  of 
cold,  the  meat  or  fish  being  either  actually  frozen,  or 
maintained  at  a  temperature  near  the  freezing  point 
without  actual  congelation.  We  will  refer  again  to 
the  subject  of  cold  storage  later. 

The  law  governing  the  sale  of  milk  in  this 
country  enacts  that  the  content  of  fat  (cream) 
shall  be  not  less  than  3  per  cent.  The  various 
preservatives  available  for  use  are  either  prohi- 
bited, or  are  restricted  as  to  the  quantity  that 

H 


100  WHAT    INDUSTRY    OWES 

may  be  added.  This  is  a  necessary  precaution,  as 
most  of  the  preservatives,  such  as  formalin  and  boric 
acid,  are  not  desirable  from  the  point  of  view  of 
health,  especially  in  the  case  of  milk,  which  is  so 
important  to  infants  and  invalids.  The  sterilisation 
of  milk  by  pasteurisation,  which  consists  in  prolonged 
heating  at  a  moderate  temperature,  is  a  useful  means 
of  safeguarding  the  public  health,  the  taste,  and 
therefore  the  palatability,  of  the  milk  being  very  little 
affected  by  the  treatment. 

Science  provides  the  means  of  distinguishing 
between  genuine  butter  and  the  various  substitutes 
now  in  common  use,  such  distinction  being  necessary 
for  the  detection  of  fraud. 

Careful  investigation  by  botanical  workers,  com- 
bined with  the  proper  application  of  manures,  has 
greatly  increased  the  yield  of  cereals,  and  the  cultiva- 
tion of  many  other  foodstuffs,  such  as  roots,  fruits, 
tea  and  coffee,  comes  more  and  more  under  scientific 
control,  with  beneficial  results.  We  propose  now  to 
consider,  as  an  example,  an  important  foodstuff,  in 
the  production  of  which  chemical,  botanical  and 
mechanical  sciences  have  played  no  mean  part. 

SUGAR. 

Sugar  is  contained  in  the  sap  of  many  trees,  such  as 
the  date,  palm,  and  the  maple,  and  in  nearly  all  fruits. 
The  main  sources,  however,  are  the  sugar-cane  and  the 
beet.  The  extraction  of  sugar  from  cane  is  said  to 
have  been  practised  in  Bengal  and  in  China  about 
800  B.C.,  and  existing  records  indicate  that  the  Egyp- 
tians, Arabs,  and  Persians  were  acquainted  with  cane 
sugar  over  1100  years  ago.  The  cane  is  now  culti- 
vated in  the  West  and  East  Indies,  in  the  Southern 
States,'and  in  South  America. 

In  the  old  method  of  manipulation  the  cane,  which 
contains  up  to  18  per  cent,  of  its  weight  in  sugar,  was 
crushed  between  rollers,  the  expressed  juice  treated 
with  milk  of  lime  to  neutralise  acidity,  filtered  and 
evaporated  to  obtain  the  crystals.  The  solid  was 
separated  by  drainage  in  perforated  casks,  and  the 
mother  liquor — which  contains  various  substances 


TO    CHEMICAL  /^eiESSf 


which  prevent  complete  crystallisation  —  appeared  on 
the  market  as  treacle  or  molasses,  or  was  fermented  to 
make  rum.  With  modern  mechanical  and  chemical 
developments  the  industry  has  been  brought  to  a 
state  of  great  efficiency.  The  introduction  of  evapo- 
rating pans  and  similar  plant  has  effected  marked 
ecofcomy  in  fuel  ;  the  crystals  are  separated  by 
centrifuges,  resulting  in  great  saving  of  time,  and  a 
leaf  has  been  taken  from  the  book  of  the  beet  sugar 
manufacturers  by  the  employment  of  a  diffusion 
process  to  replace  the  crushing.  The  cane  is  shredded 
and  soaked  in  water,  the  sugar  diffusing  through  the 
cell  walls  of  the  cane  into  the  water,  and  the  yield 
is  enormously  increased. 

The  process  of  refining  crude  sugar  generally 
consists  in  dissolving  it  in  hot  water  —  blood  being 
added  to  very  crude  sugars  to  carry  down  impurities 
in  coagulating  —  filtering,  decolourising  by  the  action 
of  animal  charcoal,  and  evaporating  to  crystallisation. 
The  products  are  separated  into  various  grades 
according  to  purity.  As  an  instance  of  the  value 
of  scientific  control  in  sugar-refining  processes,  we 
may  mention  that  one  concern  has  for  many  years 
past  effected  a  saving  of  between  £75,000  and  £100,000 
a  year  as  a  return  for  an  expenditure  of  £20,000  a 
yea,r  on  it»  laboratories  and  staffs  of  chemists. 

Sugar  was  discovered  in  beetroot  by  Marggraf,  a 
German  chemist,  in  1747,  but  it  was  not  until  1801 
that  a  factory  was  established  for  its  extraction, 
the  first  being  erected  in  Silesia  by  Achard.  In 
the  light  of  present-day  events  it  is  interesting  to 
observe  that  the  German  industry  received  consider- 
able impetus  in  its  early  years  through  the  land 
blockade  of  Prussia,  enforced  by  Buonaparte,  which 
made  the  home  production  of  sugar  a  necessity. 
Buonaparte  also  gave  encouragement  to  the  estab- 
lishment of  the  industry  in  France,  and  it  is  now 
carried  on  in  Russia,  Holland,  and  other  European 
countries.  The  juice  of  the  common  beet  contains 
only  a  low  percentage  of  sugar,  but  by  careful 
scientific  cultivation  the  yield  has  been  steadily 
increased,  so  that  some  varieties  give  over  15  Ib. 

H  2 


102  WHAT INDUSTRY   OWES 

of  sugar  per  100  Ib.  of  beet,  instead  of  about  6  Ib.  or 
less.  The  yield  of  beetroot  from  the  land  has  been 
increased  by  about  15  per  cent.,  and  the  coal  con- 
sumption in  the  process  of  extraction  has  been 
reduced  by  about  80  per  cent.  The  exhausted  sub- 
stance is  utilised  for  making  feeding  stuffs  for  cattle. 
In  the  early  method  of  extraction  the  roots  were 
cleaned  and  shredded,  the  shreds  placed  in  woollen 
bags,  and  the  juice  squeezed  out  by  hydraulic 
pressure.  This  practice  still  prevails  in  some  places, 
but  has  been  replaced  in  others  by  the  cleaner  and 
more  efficient  diffusion  process.  The  roots  are 
cut  into  thin  strips  which  are  exposed  to  the  action 
of  water  ;  the  sugar  diffuses  out  into  the  water, 
leaving  colloidal  substances  in  the  cells,  the  walls 
of  which  are  impervious  to  colloids.  The  treatment 
of  the  juice  is  similar  to  that  employed  in  the  case 
of  cane  sugar,  the  yield  of  crystallised  sugar  being 
about  70  per  cent,  of  the  sugar  in  the  root,  the  other 
30  per  cent,  remaining  in  solution  as  molasses  or 
treacle,  to  be  sold  as  such  or  used  to  make  rum. 

Increased  yields  of  sugar  in  the  crystallised  state, 
from  both  cane  and  beet,  are  largely  attributable 
to  the  Osmose  process,  based  on  Graham's  work 
on  dialysis,  and  the  Elution  processes  elaborated  by 
Steffen  and  by  Scheibler.  In  the  first  process  the 
sugar  is  allowed  to  diffuse  through  a  parchment 
membrane  into  pure  water,  the  substances  which 
prevent  crystallisation  being  unable  to  pass  through 
the  membrane.  The  solution  obtained  is  then  worked 
up  for  sugar  and  for  potassium  nitrate  which  accom- 
panies it,  while  the  remaining  liquor  goes  to  the 
distillery  for  the  manufacture  of  by-products. 

The  Elution  processes  depend  on  the  formation  of 
the  sparingly  soluble  calcium  or  strontium  salts 
formed  by  sugar — calcium  and  strontium  saccharates. 
These  salts,  obtained  by  various  methods  in  pure 
condition  from  the  sugar  in  molasses,  are  suspended 
in  water  and  decomposed  into  sugar  and  calcium  or 
strontium  carbonate,  as  the  case  may  be,  by  the  action 
of  carbonic  acid  gas. 

Other  such  processes  have  boen  devised,  but  that 


TO    CHEMICAL    SCIENCE  103 

involving  the  use  of  strontium  hydroxide  is  most 
largely  employed. 

COLD    STORAGE. 

A  valuable  by-product  of  the  beet  sugar  industry 
is  trimethylamine,  which  is  obtained  by  distillation 
from  the  final  residue  or  vinasses  of  the  Osmose 
process,  and  also  in  large  quantities  from  herring-brine 
by  distillation  with  lime.  It  is  a  gas  at  ordinary 
temperatures  condensing  in  the  cold  to  a  liquid 
which  boils  at  3.5  deg.  Cent.,  and  is  used,  as  we  have 
noticed  before,  in  the  place  of  ammonia,  in  the 
manufacture  of  potassium  bicarbonate  by  a  method 
analogous  to  the  ammonia  soda  process.  By  heating 
its  hydrochloride  with  hydrochloric  acid,  methyl 
chloride,  an  easily  condensable  gas,  is  obtained,  and 
used  for  making  certain  dyes,  and  also  as  a  freezing 
agent  in  the  technical  production  of  ice. 

The  preservation  of  food  by  cold  storage  is  of 
great  importance,  and  depends  for  its  usefulness 
upon  the  availability  of  a  large  and  cheap  supply  of 
ice.  In  the  preparation  of  ice,  advantage  is  taken 
of  the  heat  absorption  of  boiling  liquids.  A  gas 
that  can  easily  be  liquefied  by  pressure  can  be  used 
as  a  freezing  agent,  provided  that  its  other  properties 
are  not  objectionable.  The  gas  is  liquefied  by 
mechanical  pressure,  and  is  then  allowed  to  evaporate 
under  low  pressure,  the  only  heat  available  for  its 
vaporisation  being  that  contained  by  the  water  it 
is  desired  to  freeze.  The  freezing  agent  is,  of  course, 
not  destroyed,  but  can  be  recondensed  and  used 
over  again.  Gases  in  common  use  as  freezing  agents 
are  methyl  chloride,  which  liquefies  t  at  ordinary 
temperature  under  two  or  three  atmospheres  pressure, 
and  boils  under  ordinary  pressure  at  24  Centigrade 
degrees  below  zero,  ammonia  gas,  which  liquefies 
under  about  six  or  seven  atmospheres  and  boils  under 
ordinary  pressure  at  33.5  Centigrade  degrees  below  zero, 
carbonic  acid  gas,  and  cymogene  (referred  to  in 
Chapter  V.). 


104  WHAT    INDUSTRY    OWES 


CHAPTER  XV. 
BREWING. 

THE  production  of  malted  liquors  was  one  of  the 
first  industries  to  recognise  the  value  of  scientific 
investigation  in  the  elucidation  of  technological  pro- 
blems ;  but  the  industry  has  not  alone  profited — the 
field  of  work  has  proved  so  rich  in  discovery  that  an 
important  domain  of  chemical  science,  the  chemistry 
of  fermentation,  with  its  applications  to  the  leather, 
tobacco,  food  and  other  industries,  as  well  as  to  physio- 
logical science,  has  been  opened  up,  primarily  through 
the  study  of  the  principles  underlying  the  practice 
of  brewing. 

Alcoholic  liquors  were  brewed  from  grain  stuffs  in 
Egypt  as  early  as  the  4th  Dynasty  (B.C.  3000  to 
4000),  the  beverages  taking  the  place  of  wine  in 
countries  where  the  climatic  conditions  were  un- 
favourable to  the  cultivation  of  the  vine.  Although 
the  Egyptians  had  vineyards  in  the  Nile  Valley,  it  is 
probable  that  this  restriction  of  area  gave  rise  to  the 
brewing  of  grain  liquors  in  other  less  favoured  parts. 
The  earliest  fermented  liquor  known  in  Britain  was 
mead,  made  from  honey  ;  the  production  of  beer 
from  barley,  and  of  cider  from  apples  followed  in  the 
order  indicated.  All  three  beverages  were  in  use  in 
the  South  of  England  at  the  time  of  the  invasion  by 
the  Romans,  who  are  said  to  have  considerably 
improved  the  manufacture  of  beer,  which  subse- 
quently became  the  national  drink  of  the  country. 
In  the  Middle  Ages  rents  were  sometimes  paid  in  malt 
or  beer,  and  it  is  not  without  interest  to  note  that  one 
of  the  municipal  appointments  in  the  time  of  Queen 
Elizabeth  was  that  of  the  ale -taster,  a  post  held 
by  the  father  of  William  Shakespeare  at  Stratford- 
on-Avon.  Ale-tasters  were  required  to  examine 


TO    CHEMICAL    SCIENCE  105 

beer  and  ale  to  see  that  they  were  good  and  whole- 
some, and  sold  at  proper  prices.  Public  analysts 
may  now  be  considered  to  carry  on  these  duties, 
the  custom  of  appointing  ale -tasters  having  been 
discontinued  in  most  places  since  beer  and  ale 
became  excisable  commodities. 

In  normal  times  about  35  million  barrels  of  36  gallons 
are  brewed  per  year  in  the  United  Kingdom,  involving 
the  consumption  of  50  million  bushels  of  malt,  over 
60  million  pounds  weight  of  hops,  more  than  a  million 
hundredweights  of  specially  prepared  rice  and 
maize,  and  about  three  million  hundredweights  of 
sugar. 

The  question  of  water  supply  is  of  great  importance 
to  the  brewer,  the  nature  of  the  impurities  in  the 
water  used  in  mashing  greatly  influencing  the  quality 
of  the  product.  The  excellence  of  the  pale  ales  pro- 
duced at  Burton  has  been  traced  to  the  existence  in 
solution  of  large  quantities  of  calcium  and  magnesium 
sulphates  in  the  Burton  well  water.  Stout  and  porter 
are  better  brewed  with  the  softer  water  of  London  or 
Dublin,  which  does  not  contain  the  sulphates  above 
mentioned.  Sometimes  the  water  in  a  locality  can  be 
so  modified,  by  the  addition  of  the  requisite  substances, 
as  to  be  suitable  for  the  brewing  of  different  classes 
of  beer  ;  but  the  industry  has  been  largely  established 
in  districts  where  the  natural  supply  needs  no  special 
treatment. 

The  production  of  beer  from  barley  involves  three 
main  operations  :  the  conversion  of  the  grain  into 
malt ;  the  preparation  of  an  infusion  of  the  malt 
called  wort ;  and  the  fermentation  of  the  wort  by 
means  of  yeast.  Malt  is  obtained  by  keeping  barley 
in  a  moist  atmosphere  until  the  induced  germination 
has  proceeded  to  the  requisite  extent  determined  by 
examination  of  the  grain.  The  product  is  then 
heated  to  a  temperature  above  50  deg.  Cent,  to  stop 
germination.  The  infusion  known  as  wort  is  made  by 
mashing  the  finely  ground  malt  with  water,  and 
keeping  it  for  some  time  at  about  67  deg.  Cent.  The 
resulting  liquor,  after  straining  through  spent  wort, 
is  sterilised  by  boiling,  when  hops  are  added  to  impart 


106  WHAT    INDUSTRY   OWES 

a  bitter  flavour,  and  to  yield  to  the  liquor  certain 
preservative  substances.  The  liquor  is  then  cleared 
by  settling,  drawn  off,  cooled  by  "  coolers "  and 
refrigerators,  and  fermented  by  yeast. 

The  chief  change  taking  place  in  malting  barley  is 
the  production  of  an  active  body  called  diastase,  which 
has  the  power  to  convert  starch  into  sugar.  During 
malting  albuminoid  substances  are  broken  down  into 
simpler  bodies,  and  the  starch  undergoes  modifica- 
tions, assuming  a  form  more  easily  attacked  by  the 
diastase.  During  the  mashing  operation  the  starch 
is  converted  by  the  diastase  into  a  sugar,  which  is  fer- 
mentable by  yeast,  thereby  yielding  alcohol.  As  the 
finished  malt  contains  much  more  diastase  than  is 
necessary  to  convert  all  the  starch  present  into  sugar, 
starch,  in  the  form  of  flaked  rice  or  flaked  maize,  is 
sometimes  added  to  the  malt  before  mashing,  the 
final  result  being  an  increased  production  of  alcohol. 
When  desirable  the  quantity  of  sugar  in  the  wort  can 
be  increased  by.  the  direct  addition  of  invert  sugar 
or  of  glucose.  Invert  sugar,  which  contains  nearly 
equal  quantities  of  two  fermentable  sugars — dextrose 
and  laevulose — is  produced  in  large  quantities  for  the 
use  of  brewers  b^  boiling  cane  sugar  with  dilute 
mineral  acids,  whilst  glucose,  containing  two  sugars — 
dextrose  and  maltose — is  made  by  the  hydrolytic 
action  of  dilute  mineral  acids  on  starch,  an  inter- 
mediate product  being  dextrin  (British  gum).  If 
the  action  of  the  acid  were  further  prolonged  dextrose 
alone  would  be  the  main  product.  Brewers' 
glucose  contains  60—70  per  cent,  of  fermentable 
sugars. 

By  boiling,  the  wort  is  sterilised  and  concentrated, 
certain  complex  protein  bodies  are  eliminated  by 
precipitation,  diastatic  action  is  stopped,  and  the 
flavouring  and  preservative  materials  are  extracted 
from  the  hops  which  are  added  at  this  stage.  Hops 
contain  a  yellow  granular  powder  called  lupulin, 
which  is  the  most  valuable  constituent  from  the 
brewers'  point  of  view.  The  lupulin  in  new  hops  may 
amount  to  15  per  cent,  or  more,  and  contains  resins 
and  bitter  principles,  which  give  a  flavouring  and 


TO    CHEMICAL  ^SCIENCE  107 

exert  a  preservative  action  on  the  beer ;  and 
certain  volatile  essential  oils  which  also  improve  the 
flavour. 

By  fermentation  with  yeast  the  sugars  in  the  wort 
are  transformed  into  alcohol  and  carbonic  acid  gas. 
The  growth  of  yeast,  when  supplied  with  suitable 
foods,  and  its  remarkable  action  on  certain  sugars, 
have  held  the  attention  of  scientific  men  for  years. 
Liebig,  in  1839,  advanced  the  theory  that  yeast,  an 
unstable  nitrogenous  compound,  possessed  the  pro- 
perty of  communicating  this  instability  to  sugars, 
causing  them  to  decompose,  but  the  living  nature  of 
yeast  was  not  then  recognised.  About  thirty  years 
later  Liebig' s  views  were  overthrown  by  Pasteur  after 
a  long  controversy,  and  Liebig  was  compelled  to  make 
certain  modifications  in  his  theory.  As  the  result  of 
a  series  of  epoch-making  experiments,  Pasteur  came 
to  the  conclusion  that  yeast  was  an  organism  capable, 
under  certain  conditions,  of  maintaining  its  life  with- 
out the  aid  of  atmospheric  oxygen,  that  element  being 
derived  from  sugars,  the  presence  of  which  fulfilled 
the  conditions.  The  maximum  fermentative  power 
of  yeast  was  therefore  attained  in  the  absence  of 
atmospheric  oxygen.  This  theory  held  the  field  until 
1892,  when  the  researches  of  Adrian  J.  Brown  showed 
it  to  be  untenable.  In  1897  Buchner  demonstrated 
that  the  living  yeast  cell  is  not  necessary  for  fermen- 
tation, but  that  the  clear  liquid  extracted  from  the 
yeast  by  heavy  pressure  served  the  purpose.  He 
proved  conclusively  that  the  cause  of  the  fermentation 
is  an  enzyme,  which  he  called  zymase.  Further  light 
has  been  thrown  on  the  problem  by  Arthur  Harden, 
who  separated  the  active  liquid  into  two  inactive 
constituents — the  enzyme  and  the  co -enzyme — which, 
when  remixed,  became  once  more  active.  Harden 
has  also  shown  the  importance  of  phosphates  in 
accelerating  the  change.  To  summarise:  the  living 
yeast  contains  and  reproduces  an  active  non-living 
body  which  is  capable  of  converting  sugars  into 
alcohol  and  carbonic  acid  gas.  The  yeast  grows 
at  the  expense  of  certain  foods  present  in  the 
wort. 


108  WHAT   INDUSTRY   OWES 

Utilisation  of  Waste  Products. — Dried  yeast  is  used 
as  a  cattle  food,  and  as  the  source  of  an  excellent 
substitute  for  meat  extract.  Carbonic  acid  gas  is 
compressed  and  used  for  the  aeration  of  beer  and 
mineral  waters. 


TO    CHEMICAL    SCIENCE  109 


CHAPTEB  XVI. 
ALCOHOL,  WINES  AND  SPIRITS. 

ALCOHOL  is  one  of  the  most  important  chemical 
products.  We  have  already  referred  to  it  as  a 
solvent,  in  which  capacity  it  is  of  great  service  to  the 
chemist  in  the  laboratory  as  well  as  in  industrial 
operations  involved  in  the  manufacture  of  transparent 
soap,  varnishes,  French  polish,  collodion,  and  celluloid. 
It  is  not  only  as  a  solvent,  however,  that  it  figures 
extensively  in  the  arts  and  manufactures.  It  is  used 
in  the  technical  preparation  of  chloroform,  iodoform, 
fulminates,  ether,  acetic  acid,  and  many  other  bodies. 
For  certain  purposes — such  as  the  production  of  some 
kinds  of  whiskey  and  brandy,  and  of  liqueurs,  and  in 
the  manufacture  of  scents,  fine  chemicals  and  drugs — 
only  alcohol  of  a  considerable  degree  of  purity  can 
be  used,  and  the  expense  is  correspondingly  high. 

Alcohol  is  made  from  the  cheapest  starchy  materials 
available,  such  as  potatoes,  maize,  turnips,  molasses. 
The  raw  material  is  mashed  with  about  5  per  cent, 
of  malt,  and  fermented  in  the  usual  way.  After 
distillation  in  a  Coffey  still,  the  spirit  is  diluted  with 
water,  filtered  through  wood  charcoal  to  remove 
fusel  oil  and  redistilled  through  a  fractionating 
column.  The  products  are  separated  into  three 
grades  :  first  runnings,  and  first  and  second  quality 
spirits.  The  first  runnings,  containing  about  95  per 
cent,  of  alcohol  with  a  small  quantity  of  aldehyde, 
may  be  used  for  burning  and  in  manufactures  where 
the  impurities  give  rise  to  no  deleterious  effects. 
The  first  and  second  qualities,  which  are  96  to  97  per 
cent,  in  strength  and  contain  only  traces  of  aldehyde — 
the  second  quality  also  containing  a  small  quantity 
of  fusel  oil — are  known  as  silent  spirit,  because  they 
afford  no  evidence  of  their  source.  These  qualities 


110  WHAT    INDUSTRY    OWES 

are  used  for  drinking  purposes — liqueurs  and  factitious 
brandy  and  whiskey — and  for  pharmaceutical  pre- 
parations. 

Absolute  alcohol,  containing  99  per  cent,  or  more  of 
alcohol,  is  obtained  by  dehydrating  the  finer  spirits 
by  redistilling  with  about  half  their  weight  of  quick- 
lime, whilst  100  per  cent,  alcohol  may  be  prepared  by 
the  addition  of  a  small  quantity  of  metallic  sodium 
to  absolute  alcohol  and  further  redistillation. 

The  denaturing  of  industrial  spirit — rectified  spirit 
and  first  runnings — consists  in  adding  to  the  alcohol, 
to  render  it  undrinkable,  some  substance  or  substances 
which  cannot  be  profitably  separated,  and  which  have 
the  minimum  harmful  effect  in  the  |  processes 
demanding  the  use  of  such  spirit.  Were  it  not  for 
the  fact  that  in  most  countries  the  Governments  per- 
mit the  sale  and  use  of  denatured  or  undrinkable  spirit 
free  of  duty,  the  high  duty  on  such  spirit  would 
render  its  use  in  ordinary  manufactures  prohibitive 
from  the  point  of  view  of  economy,  and  the  absence 
of  such  facilities  would  prove  a  great  hindrance  to 
the  industries  concerned. 

Methylated  spirit  is  duty  free,  and  may  be  used 
instead  of  rectified  spirit— spirits  of  wine — in  the 
manufacture  of  chloroform  and  varnishes,  for  pre- 
serving anatomical  specimens  and  for  many  other 
purposes.  It  was  originally  made  by  adding  about 
10  per  cent,  of  methyl  alcohol — wood  spirit — a  product 
of  the  destructive  distillation  of  wood,  which  has  a 
sharp  fiery  flavour  and  contains  substances  dis- 
agreeable both  to  taste  and  smell.  The  presence  of 
wood  spirit,  however,  has  little  or  no  effect  on  the 
industrial  uses  of  alcohol,  from  which,  moreover,  it 
cannot  be  profitably  removed.  The  main  use  of 
wood  spirit,  therefore,  is  for  denaturing  purposes  ; 
but  it  is  also  employed  as  a  solvent  for  resins  and  in 
the  manufacture  of  dyes,  its  characteristic  component 
CHS,  appearing  in  this  role  as  a  constituent  of  the 
intermediate  products  methylaniline  and  dimethyl - 
aniline,  bases  largely  used  for  the  production  of  basic 
dyes,  such  as  methyl  violet — the  colouring  matter  of 
recording,  copying,  and  typewriting  inks — malachite 


TO    CHEMICAL    SCIENCE  111 

green,  and  methylene  blue.  The  processes  for  the 
extraction  and  purification  of  wood  spirit,  however, 
were  in  the  course  of  time  so  far  improved,  that  its 
purity  eventually  unfitted  it  for  use  alone  as  a  de- 
naturant  ;  it  is  still  universally  used  for  the  purpose, 
but  with  the  enforced  addition  of  other  more  dis- 
agreeable substances,  such  as — in  the  case  of  ordinary 
methylated  spirit — not  less  than  f  per  cent,  of 
paraffin  of  specific  gravity  0.800.  For  some  manu- 
facturing purposes  the  paraffin  is  a  disturbing  factor, 
causing  turbidity  on  mixing  with  water,  and  being 
unsatisfactory  in  other  respects.  To  obviate  these 
disadvantages,  various  denatured  spirits  are  now 
made,  containing  from  2  to  10  per  cent,  of  wood 
spirit  with  a  smaller  quantity  of  other  substances  of 
unpleasant  taste,  the  choice  being  determined 
according  to  the  purpose  for  which  the  spirit  is  to  be 
employed.  Thus,  in  the  manufacture  of  transparent 
soap,  a  spirit  denatured  with  wood  spirit,  castor  oil 
and  caustic  soda  is  useful ;  in  making  mercury 
fulminate,  a  mixture  of  wood  spirit  with  pyridine 
bases  forms  a  suitable  denaturant ;  and  in  making 
celluloid  the  spirit  may  be  mixed  with  wood  spirit, 
camphor,  and  benzene.  Other  denaturants  include 
toluol,  xylol,  wood  vinegar,  turpentine,  animal  oil, 
chloroform,  iodoform,  and  ethyl  bromide,  according 
to  the  needs  of  the  industry  for  which  the  spirit  is 
required. 

Wines. — The  production  of  wines  by  the  fermen- 
tation of  grapes  is  an  industry  of  great  antiquity. 
Several  words  in  Hebrew  are  translated  in  our  Old 
Testament  as  wine,  and  we  find  it  associated  with  Noah, 
who,  when  he  began  to  be  an  husbandman,  planted 
a  vineyard,  drank  of  the  wine  and  was  drunken. 
Fermented  grape  juice  was  a  beverage  of  the  ancient 
Egyptians  five  or  six  thousand  years  before  our  time. 

Wine  is  made  by  allowing  the  juice  of  grapes 
to  ferment  spontaneously,  the  organism  inducing 
the  change  occurring  plentifully  in  the  air  dust  of 
vine-growing  countries,  and  speedily  infecting  any 
sugary  liquor  freely  exposed  to  the  air.  When  white 
wine  is  the  product  desired,  all  the  seeds  and  husks 


112  WHAT    INDUSTRY   OWES 

of  the  grapes  are  carefully  excluded,  because  it  is 
from  these  that  the  colouring  matter  of  red  wines 
is  extracted  by  the  alcoholic  liquid  produced  by 
fermentation.  The  seeds  and  husks  also  give  up 
a  small  quantity  of  tannin,  which  acts  favourably 
as  a  preservative  of  the  red  wines,  and  prevents 
ropiness.  Sparkling  wines,  such  as  champagne,  are 
made  by  dissolving  sugar  in  a  still  wine  and  allowing 
it  to  undergo  secondary  fermentation  in  the  bottle. 
Ordinarily,  wine  consists  of  a  mixture  of  alcohol 
and  water,  containing  from  7  to  17  per  cent,  of  the 
former,  together  with  smaller  quantities  of  sugar, 
bitartrate  of  potash,  glycerine,  and  other  bodies, 
including  traces  of  flavouring  matters.  If  a  sugar 
solution  contains  much  more  than  30  per  cent,  of  its 
weight  of  sugar  it  cannot  be  fermented  by  yeast. 
A  solution  of  alcohol  of  16-17  per  cent,  strength 
also  inhibits  the  action  of  yeast,  and  it  follows, 
therefore,  that  fermented  liquor  cannot  contain  more 
than  this  percentage.  Should  a  wine  of  greater 
strength  be  desired,  it  can  be  obtained  only  by  the 
addition  of  stronger  distilled  spirit.  Thus  the 
strongest  port  wine,  as  produced  by  the  ordinary 
fermentation,  contains  not  more  than  16  to  17  per 
cent,  of  alcohol,  but  it  can  be  "  fortified  "  if  necessary 
by  the  addition  of  absolute  alcohol  or  rectified  spirit 
in  the  proper  proportion.  For  this  purpose  it  is 
desirable  to  use  the  strongest  alcohol  obtainable, 
as  if  a  weaker,  e.g.,  less  than  90  per  cent.,  were  used, 
the  water  necessarily  added  with  it  would  dilute 
the  other  ingredients  of  the  wine  to  an  abnormal 
extent,  and  modify  unfavourably  its  original 
characteristics. 

Spirits  may  be  divided  roughly  into  two  classes,  ( 1 ) 
pot-still  spirits,  including  brandy  and  whiskey  ;  and  (2) 
gin  spirits,  made  by  the  suitable  treatment  of  plain 
rectified  spirit  or  alcohol.  The  manufacture  of 
spirits  was  made  possible  only  by  the  discovery 
of  the  process  of  distillation,  and  is  not,  therefore, 
of  such  antiquity  as  the  wine  and  beer  industries. 
The  products  differ  from  fermented  liquors  from  which 
they  are  produced,  mainly  in  the  larger  content  of 


TO    CHEMICAL    SCIENCE  113 

alcohol,  in  the  absence  of  non-volatile  matter,  and 
in  the  possession  of  certain  distinct  flavouring  matters, 
either  occurring  naturally  or  added  purposely. 
Cognac  brandy  is  made  by  distilling  from  a  pot 
the  fermented  juice  of  a  small  variety  of  grape, 
the  alcohol  passing  over  among  the  first  products 
of  the  distillation.  The  spirit  contains  about  50  per 
cent,  of  alcohol,  and  owes  its  aroma  and  flavour 
to  small  quantities  of  capric  (cenanthic)  ester  derived 
from  the  wine.  The  colour  of  genuine  old  brandy 
is  due  to  colouring  matter  extracted  from  the  wood 
of  the  casks  in  which  it  is  stored,  its  astringent 
flavour  being  due  to  tannin  from  the  same  source. 
New  brandy  is  coloured  to  resemble  the  old  by  the 
addition  of  caramel  (sugar — generally  starch  sugar — 
heated  to  about  190  deg.  Cent.),  astringency  being 
sometimes  imparted  by  an  infusion  of  tea. 

Whiskey  is  made  from  malted  barley,  or  from 
a  mixture  of  unmalted  and  malted  grain,  the  mixture 
being  dried  over  a  peat  fire,  from  which  the  whiskey 
derives  its  smoky  flavour.  By  a  washing  operation 
similar  to  that  practised  by  brewers,  a  wort  is  produced 
which  is  cooled  quickly  by  refrigerators  and  fermented 
by  purified  brewers'  yeast,  as  completely  as  possible, 
at  a  low  temperature.  These  conditions  combine 
to  ensure  the  production  of  a  good  liquor  free  from 
sourness,  and  with  the  minimum  of  wasteful  and 
objectionable  impurities  such  as  fusel  oil  and 
aldehyde.  When  the  fermentation  stops,  the  liquor 
is  distilled  from  a  large  copper  still — up  to  12,000 
gallons — sometimes  with  the  addition  of  soap  to 
prevent  undue  frothing  until  all  the  alcohol  has 
passed  over.  The  distillate  from  this  operation 
known  as  "  low  wines  "  is  poor  in  alcohol  and  requires 
a  second  distillation.  The  residue  remaining  in 
the  still  contains  a  small  quantity  of  lactic  acid, 
which  is  often  recovered  and  used  as  a  substitute 
for  acetic  and  tartaric  acids  in  processes  where  a 
weak  acid  is  required,  and  where  the  chemical  nature 
of  the  acid  is  not  of  first  importance.  The  second 
distillate  is  collected  in  three  fractions  called  "  fore- 
shoots,"  "  clean  spirits,"  and  "  feints."  The  clean 


114  WHAT    INDUSTRY   OWES 

spirit  is  a  strong  whiskey  containing  about  60  per 
cent,  of  alcohol.  It  is  generally  diluted  with  water 
to  about  40  per  cent,  before  being  sold  to  the  customer, 
the  minimum  being  fixed  by  Act  of  Parliament  (1879) 
at  37  per  cent,  by  weight.  The  fore-shoots  are 
highly  impure,  containing  fatty  acids  and  other 
substances,  while  the  "  feints "  consist  chiefly  of 
fusel  oil,  a  mixture  of  higher  boiling  alcohols,  used 
in  recent  years  as  a  raw  material  in  the  production 
of  synthetic  rubber,  and  also  as  a  solvent.  The 
"  spent  lees  "  remaining  in  the  still  is  a  waste  for 
which  as  yet  no  useful  application  has  been  found. 

British  brandy  and  whiskey  prepared  in  a  similar 
way  from  potato  starch  need  to  be  freed  from  a  rather 
larger  percentage  of  fusel  oil  than  does  barley  spirit. 

Rum,  which  is  made  by  fermenting  treacle  or 
molasses,  and  twice  distilling  the  product,  owes  its 
flavour  to  formic  and  butyric  esters,  and  is  coloured 
either  by  ageing  in  wood,  or  artificially  by  means  of 
caramel. 

The  plain  spirit,  i.e.,  a  mixture  containing  water 
and  alcohol  only,  which  is  used  to  make  gin  and 
liqueurs,  is  produced  by  fermenting  a  mixture  of 
malted  and  unmalted  grain,  and  distilling  the  resulting 
alcoholic  liquor  or  "  wash  "  through  a  special  fraction- 
ating apparatus  such  as  the  Coffey  still.  WThen 
distillation  takes  place  from  a  pot-still  little  fraction  - 
ation  occurs,  and  a  large  proportion  of  the  lower 
and  higher  boiling  substances  pass  over  with  the 
alcohol,  necessitating  a  second  distillation ;  but  by 
the  use  of  a  contrivance  such  as  the  Coffey  still, 
which  is  too  complicated  for  description  here,  the 
greater  proportion  of  the  impurities  can  be  eliminated 
by  one  distillation. 

Gin  is  made  by  adding  some  substance,  such  as 
juniper  or  liquorice  root,  to  the  spirit,  and  re-dis- 
tilling from  a  pot,  when  the  distillate  passing  over 
carries  with  it  the  flavouring  matter  extracted 
from  the  root.  Liqueurs  are  made  by  dissolving 
large  quantities  of  sugar  in  the  alcohol  with  various 
flavouring  and  colouring  materials. 


TO    CHEMICAL    SCIENCE  115 


CHAPTER    XVII. 

TOBACCO,  INKS,  PENCILS,  &c. 

TOBACCO  is  cultivated  in  many  countries,  especially 
in  Virginia  and  the  Southern  States,  in  Mexico, 
Cuba,  and  the  West  Indies,  in  Asia  Minor  and  Persia, 
in  India,  China,  and  Borneo,  and  in  South  Africa, 
and  affords  scope  for  the  botanist,  biologist,  and 
chemist,  both  in  the  plantations  and  in  the  factories. 
In  the  days  of  Columbus  the  natives  of  the  West 
Indies  smoked  the  rolled  leaf,  the  Mexicans  and 
North  American  Indians  used  pipes,  and  the  Aztecs 
and  Hispaniolan  Indians  applied  forked  tubes  to 
the  nostrils.  Tobacco  was  introduced  into  Europe 
by  Hermandez  de  Toledo  in  1559,  into  England  by 
Sir  John  Hawkins  in  1565,  and  its  use  speedily 
became  very  general  in  spite  of  all  forms  of  opposition. 
Smoking  was  the  butt  of  the  wits,  denounced  by 
the  clergy,  and  condemned  by  rulers  and  popes, 
offenders  being  subject  to  severe  punishment.  In 
Turkey  it  was  a  capital  offence,  and  in  the  canton 
of  Berne  was  prohibited  as  an  addition  to  the  deca- 
logue. In  England  King  James  I.  issued  a  "  Counter  - 
blaste  to  Tobacco,"  in  which  smoking  was  described 
as  "  a  custom  loathsome  to  the  eye,  hateful  to  the 
nose,  harmful  to  the  brains,  dangerous  to  the  lungs" 
.  .  .  as  "  resembling  the  horrible  smoke  of  the  pit 
that  is  bottomless  ;  "  but  although  often  the  subject 
of  violent  diatribes,  it  remains  at  the  present  day 
a  most  popular  luxury  among,  both  rich  and  poor, 
and  we  may  contrast  the  views  of  the  Stuart  King 
with  those  of  Kingsley  indicated  in  "  Westward  Ho  !  " 
"  When  all  things  were  made  none  was  made  better 
than  Tobacco  ;  to  be  a  lone  man's  Companion,  a 
bachelor's  Friend,  a  hungry  man's  Food,  a  sad  man's 

r 


116  WHAT    INDUSTRY   OWES 

Cordial,  a  wakeful  man's  Sleep,  a  chilly  man's  Fire. 
There's  no  herb  like  it  under  the  canopy  of  Heaven." 

Tobacco  is  rarely  prescribed  in  medicine  or 
employed  in  pharmacy  ;  but  it  is  well  known  that 
smoking  in  moderation  acts  as  a  sedative,  and  is  often 
beneficial  in  promoting  expectoration  in  cases  of 
asthma.  Snuff,  which  is  prepared  from  the  ribs 
and  stems  of  the  tobacco  leaf,  is  occasionally  recom- 
mended to  excite  the  secretion  of  mucus  from  the 
nasal  membrane.  The  absorption  of  very  small 
quantities  of  nicotine  is  stimulating  to  mind  and 
body,  but  in  excess  the  effect  is  depressing,  narcotic, 
and  injurious  to  the  sight.  Much  depends  upon 
the  constitution  of  the  smoker,  habituation,  and  other 
circumstances.  But  we  have  digressed  from  our 
object.  The  industry  is  an  important  one  from  the 
financial  standpoint.  In  normal  times  we  spend 
between  four  and  five  million  pounds  on  imported 
tobacco — more  than  twice  the  expenditure  on  dyes — 
and  the  smoker  pays  very  heavily  to  the  Exchequer  for 
his  luxury.  He  is  protected,  however,  by  the 
inspection  of  imported  tobacco  by  the  Government 
laboratory.  Many  thousand  samples  are  examined 
annually,  in  accordance  with  the  legislation  for- 
bidding adulteration  or  excess  of  moisture,  offenders 
being  liable  to  heavy  penalties.  Tobacco  was  formerly 
much  adulterated  with  leaves  of  rhubarb,  cabbage, 
dock  and  the  like,  as  well  as  with  sugar,  starch, 
and  gum ;  but  although  sweetening  matters  such 
as  sugar,  treacle,  liquorice,  and  glycerine  are  occasion- 
ally present  in  imported  tobacco,  adulterants  are 
now  comparatively  rarely  detected. 

The  chemical  composition  of  tobacco  is  highly 
complex,  the  determinable  constituents  numbering 
over  twenty.  The  quality  of  the  leaf  is  attributed 
to  the  nature  of  the  soil  where  it  is  grown,  though  the 
finished  product  must  remain  largely  a  matter  of  taste. 
The  methods  of  manufacture  depend  on  the  variety 
of  tobacco  and  the  purpose  for  which  it  is  intended ; 
and  the  processes  are  supervised  more  and  more 
by  men  of  hcience  who  can  render  useful  assistance 
in  many  ways,  such  as  the  prevention  of  mouldiness 


TO    CHEMICAL    SCIENCE  117 

and  the  utilisation  of  waste.  The  leaves,  when 
harvested,  are  allowed  to  wither  to  a  certain  extent, 
and  then  undergo  shed-drying  or  sweating  in  moderate 
heaps  covered  with  matting.  The  leaf  cells  transpire 
carbohydrates,  albuminoid  matters  become  con- 
verted into  amides,  and  the  heat  generated  effects 
the  drying  of  the  leaves,  which  then  undergo  fermenta- 
tion in  bundles  arranged  in  large  heaps.  Tons  of 
tobacco  are  thus  allowed  to  decompose  rapidly  at 
a  temperature  usually  kept  below  50  deg.  Cent., 
the  bundles  being  turned  about  so  that  all  are  equally 
affected.  Suchsland  is  stated  to  have  prepared 
cultures  of  the  bacteria  of  the  fermentation,  and  to 
have  transferred  them  from  fine  West  Indian  to 
German  tobacco  in  the  course  of  fermentation, 
with  remarkable  improvement  to  the  latter. 

The  leaf  as  imported  to  this  country  is  subjected 
to  secondary  fermentation  after  the  addition  of 
5  to  25  per  cent,  of  water,  and  is  dried  or  stoved  on 
heated  open  trays,  or  in  closed  ovens  subjected 
sometimes  to  injections  of  steam,  different  methods 
of  treatment  affecting  the  flavour  of  the  product. 
The  content  of  nicotine  in  the  leaf  varies  from  1  to 
5,  though  it  is  sometimes  as  high  as  8  per  cent.;  a 
single  cigar  often  contains  a  deadly  dose,  but  it  retreats 
from  the  heat  as  the  tobacco  burns  and  accumulates 
in  the  stump  or  butt.  By  passing  a  current  of  steam 
through  a  mixture  of  lime  and  tobacco  dust,  neutralis- 
ing the  resulting  liquid  with  sulphuric  acid,  and  adding 
caustic  potash,  nicotine  is  liberated  and  may  be 
dissolved  in  ether,  the  solution  yielding  almost 
pure  alkaloid,  which  is  employed  in  the  manufacture 
of  insecticides  for  horticultural  purposes. 

We  propose  now  to  deal  with  a  few  industries  under 
scientific  control  which  employ  chemical  products, 
and  relate  to  commodities  in  everyday  use. 

Inks. — In  early  times  the  thoughts  and  actions  of 
men  were  incised  on  stone,  impressed  on  clay  or  wax, 
or  carved  on  ivory,  metal  or  wood ;  but  with  the 
introduction  of  papyrus,  which  we  have  mentioned  in 

i  2 


118  WHAT    INDUSTRY   OWES 

the  chapter  on  cellulose,  characters  were  formed  by  the 
application  of  coloured  fluids  by  means  of  a  brush  or 
reed.  The  word  "  ink  "  is  associated  more  closely 
with  the  more  ancient  methods,  being  derived  from 
the  Greek  encaustos  (burnt  in),  and  from  the  Latin 
encaustum  (the  purple-red  ink  used  by  the  later 
Roman  Emperors).  The  oldest  writing  material 
appears  to  have  been  composed  of  very  finely  divided 
carbon  hi  a  solution  of  an  adhesive  substance,  which 
held  the  carbon  in  suspension  and  fixed  it  to  the 
papyrus.  Ink  of  this  sort  has  been  found  on  ancient 
Egyptian  papyri,  and  was  no  doubt  also  in  use  in 
China  at  least  as  early.  Carbon  inks  are  permanent 
and  very  resistant  to  chemical  action,  but  there  is  a 
tendency  for  the  pigment  to  sink  in  the  liquid  unless 
it  is  frequently  stirred.  Printing  inks  also  consist 
mainly  of  carbon  with  well-boiled  drying  oils  and  soap 
or  resinous  matter.  For  ordinary  writing  purposes, 
however,  carbon  inks  were  superseded  centuries  ago 
by  iron-tannin  inks,  prepared  from  a  decoction  of 
galls  with  copperas  and  gum  arabic,  formerly  home 
made,  but  now  produced  in  common  with  many  other 
domestic  requirements  on  an  industrial  scale.  The 
action  of  the  tannin — from  the  decoction  of  galls — on 
the  copperas  produced  a  precipitate,  which,  being 
insoluble,  formed  a  deposit,  but  manufacturers 
avoided  these  conditions  by  excluding  air  to  prevent 
oxidation,  and  by  adding  soluble  colouring  matter. 
Good  writing  ink  should  remain  sweet  and  fluid  when 
exposed  to  air,  should  be  permanent  to  light  under 
ordinary  atmospheric  conditions,  and  not  contain  an 
excess  of  free  acid  which  would  injure  the  pen  and 
paper,  though  the  ink  is  not  always  to  be  blamed  for 
these  contingencies.  In  the  middle  of  the  eighteenth 
century  logwood  was  added  ;  in  many  cases  it  replaced 
the  tannin  entirely,  and  still  forms  the  basis  of  some 
inks.  Coloured  inks  have  also  been  prepared  with 
cochineal  and  indigo,  and  with  the  introduction  of 
coal  tar  dyes  a  large  variety  of  easily  running  inks, 
specially  suitable  for  stylographic  and  fountain  pens, 
have  been  rendered  available,  though  it  should  be 
remarked  that  they  are  not  regarded  as  so  permanent 


TO    CHEMICAL    SCIENCE  119 

as  the  iron-gallo-tannates.  Many  typewriter  ribbons 
are  prepared  with  coal  tar  dyes,  and  are  therefore  open 
to  this  objection,  the  ink  being  fairly  easily  removed  by 
chemical  means.  Inks  highly  sensitive  to  tampering 
are  employed  for  bankers'  cheques,  and  the  detection 
of  forgeries  often  depends  on  the  effects  produced  by 
treatment  with  various  chemical  reagents.  Copying 
inks  are  concentrated  writing  solutions,  usually  con- 
taining two  or  three  times  the  amount  of  colouring 
and  thickening  matter.  It  is  probably  no  news  to 
engineers  that  James  Watt  invented  the  copying 
press,  the  patent  for  which  was  granted  to  him  in  1780. 
He  employed  an  ink  prepared  from  a  decoction  of 
Aleppo  galls,  green  copperas  and  gum  arabic,  which 
is  much  the  same  as  the  inks  now  used  for  the  same 
purpose,  except  that  they  contain  soluble  dyes, 
dextrin  or  sugar,  and  in  some  cases  glycerine.  Iron 
tannin  inks,  when  exposed  to  the  air,  become  oxidised 
and  insoluble,  so  that  they  cannot  be  copied. 

The  juices  of  various  plants  have  long  been  utilised 
as  marking  inks,  such  plants  including  the  ink  plant 
of  New  Granada  and  New  Zealand,  the  cashew  nut,  the 
Indian  marking  nut  and  others.  Modern  marking 
inks,  which  should  withstand  the  action  of  soap  and 
alkaline  and  acid  liquids,  mainly  consist  of  solutions 
of  silver  nitrate  coloured  with  lampblack  and  thick- 
ened with  gum.  Salts  of  gold,  platinum,  manganese, 
and  of  other  metals  have  been  used  for  the  same 
purpose. 

Pencils. — We  have  already  noted  the  use  of  the 
brush  for  applying  characters  to  papyrus.  The  word 
"  pencil  "  is  derived  from  the  Latin  penicillus,  a  small 
tail.  The  use  of  charcoal  and  similar  materials  followed 
and,  at  an  early  date,  metallic  lead  was  employed  to 
mark  parchment  and  papers ;  hence,  the  term 
"  blacklead "  as  applied  to  pencils,  denoted  the 
blacker  mark  of  graphite  or  plumbago.  As  a  matter 
of  fact,  the  graphite  used  for  making  pencils  consists 
almost  entirely  of  carbon  and  contains  no  lead. 
It  has  been  employed  for  this  purpose  since  the 
seventeenth  century,  and  for  a  long  time  was  obtained 
almost  exclusively  from  the  Borrowdale  mines  in 


120  WHAT    INDUSTRY   OWES 

Cumberland,  being  mined  in  compact  grey-black 
masses,  cut  into  thin  plates,  then  into  rectangular 
sticks  and  cased  in  wood.  The  mine  was  guarded 
by  an  armed  force,  and,  to  maintain  the  monopoly, 
an  Act  was  passed  restricting  the  working  to  only 
six  weeks  in  the  year  ;  for  the  remainder  it  was 
flooded  to  prevent  theft.  The  best  quality  was 
exhausted  early  in  the  nineteenth  century,  and  the 
pencil  manufacturers  turned  their  attention  to 
utilising  accumulations  of  waste  from  cuttings  of 
the  original  masses,  which  were  crushed  and  mixed 
with  other  materials. 

One  of  the  results  of  such  experiments  was  the 
introduction  of  varying  degrees  of  hardness  in  which 
respect  the  native  graphite  was  never  uniform. 
Conte,  of  Paris,  is  credited  with  the  method  now 
generally  employed,  of  making  pencils  from  finely 
ground  graphite  mixed  with  varying  proportions  of 
clay,  allowing  for  fourteen  degrees  of  hardness  and 
softness  ranging  from  6  H  to  6  B  with  HB  (hard 
and  black),  and  F  (firm)  as  the  middle  degrees. 

Graphite  has  since  been  found  in  many  parts  of 
the  world.  The  crystalline  variety  occurs  in  Ceylon, 
but  is  not  sufficiently  black  for  pencil-making ; 
the  massive,  which  occurs  in  Bohemia,  Bavaria, 
and  Mexico,  is  much  blacker.  It  is  ground  very 
fine,  mixed  with  water,  and  passed  through  tanks 
to  allow  the  heavier  particles  to  fall,  the  finer  particles 
passing  on  to  five  or  six  successive  tanks,  when  the 
necessary  degree  of  fineness  having  been  obtained, 
it  is  mixed  with  suitable  clay  which  has  been  washed 
in  the  same  manner.  The  mixture  is  submitted 
to  further  grinding,  squeezed  in  bags  to  remove 
superfluous  water  and  forced  through  tubes  to 
produce  strips  of  the  required  shapes  and  sizes,  which, 
when  dried  and  baked,  are  ready  for  casing  in  wood. 

The  wood  mostly  used  for  making  pencils  is  that 
of  red  cedar,  not  the  cedar  of  Lebanon,  but  the 
Juniperus  Virginiana  which  grows  in  Florida, 
Alabama,  and  Tennessee,  and  lends  itself  well  to 
the  purpose  on  account  of  its  soft  character  and 
straightness  of  grain.  It  is  usually  cut  into  short  thin 


TO    CHEMICAL    SCIENCE  121 

slats  of  the  length  of  a  pencil,  though  sometimes  of 
several  lengths,  and  sufficiently  wide  for  making 
from  two  to  six  pencils.  The  slats  are  grooved  to 
receive  the  lead  and,  when  glued  together,  can  be 
cut  into  the  corresponding  number  of  pencils,  which 
are  then  smoothed  by  machinery,  polished,  stamped 
with  the  letters  indicating  the  degree  of  hardness, 
and  the  makers'  name,  tied  into  bundles,  and  generally 
prepared  for  sale.  Coloured  pencils  are  made  from 
special  clay  finely  ground  with  colour,  such  as  Prussian 
blue,  or  vermilion,  and  mixed  with  a  binding  material, 
pressed  into  sticks  which  are  toughened  by  boiling 
in  a  mixture  of  special  fats  and  waxes  before  they  are 
placed  in  the  slats.  For  copying-ink  and  indelible 
pencils,  an  aniline  dye  is  used,  the  colour  being 
soluble  in  water  in  order  that  impressions  may  be 
taken  on  tissue  paper.  With  the  demand  for  pencils 
steadily  increasing  and  the  supply  of  suitable  cedar 
becoming  quickly  exhausted,  manufacturers  will  be 
obliged  to  use  other  woods,  or  users  must  be  content 
with  mechanical  pencils.  The  industry  is  restricted 
to  comparatively  few  firms,  the  majority  being  of 
long  standing.  Details  of  manufacture  are  largely 
kept  secret,  but  enough  has  been  said  to  indicate  that 
the  industry  owes  much  to  chemical  science,  in  tho 
selection,  mixing,  And  general  treatment  of  materials, 
and  to  mechanical  science  in  the  invention  of  labour- 
saving  machinery  for  the  processes  involved. 

Other  domestic  requirements,  such  as  blacklead 
(stove  polish),  and  blacking,  for  leather,  are  now  pro- 
duced under  scientific  control.  Black  lead  for  produc- 
ing a  polished  black  surface  on  iron  is  made  from  the 
massive  graphite.  Blacking  is  made  of  a  variety  of 
materials  and  consists  essentially  of  some  black  pig- 
ment, such  as  animal  charcoal  (bone  black),  incorporated 
with  substances  capable  of  taking  a  polish  by  friction. 
A  mixture  of  bone  black,  sperm  oil,  molasses  and 
vinegar  forms  a  typical  blacking,  while  other  kinds 
contain  starch  as  ground  material  with  tannate  of 
iron  as  colouring  agent,  and  gum  arabic  as  a  binding 
material. 


122  WHAT    INDUSTRY    OWES 


CHAPTEB  XVIII. 
GASES. 

IN  the  article  on  coal,  we  gave  a  brief  description 
of  the  manufacture  and  purification  of  one  of  its 
principal  decomposition  products — coal  gas.  Before 
drawing  our  work  to  a  conclusion,  we  propose  to  say 
something  of  other  gases,  little  known  to  those  who 
do  not  use  them,  and  far  simpler  in  their  constitution 
than  coal  gas.  Discovered  by  science,  their  manu- 
facture is  the  outcome  of  scientific  investigation,  and 
not  the  mere  retorting  of  a  complex  naturally 
occurring  substance. 

The  word  gas  is  said  to  have  been  introduced  by 
the  Flemish  chemist,  Van  Helmont — sixteenth  cen- 
tury— being  associated  with  the  Dutch  geest,  a  spirit 
or  ghost,  Danish  and  German,  geist,  from  the  same 
root  as  the  Anglo-Saxon  gaestlic,  ghastly.  To  the 
mediaeval  mind,  the  air  was  a  mystery,  something 
supernatural :  it  could  not  be  seen  or  smelled,  but 
could  be  felt  and  heard.  Gradually  the  idea  of  the 
material  nature  of  the  air  was  developed  by  the 
schools,  but  owing  to  the  vague  nature  of  the  entity 
concerned  and  the  difficulty  of  handling  it,  little 
progress  was  made  with  experimental  investigation 
until  the  middle  of  the  seventeenth  century.  No 
variety  was  recognised  and  everything  of  the  nature 
of  air  was  classed  as  air,  until  the  advent  of  methodical 
experiment  and  logical  deduction  laid  the  foundations 
of  this  fundamental  department  of  knowledge. 

A  gas  is  physically  the  simplest  form  of  matter  ;  the 
laws  governing  its  behaviour  are  less  complex  than  those 
regulating  the  conduct  of  solids  and  liquids.  To  the 
recognition  of  this  fact  and  the  application  of  the 
principle  of  defeating  the  weakest  enemy  first,  science 


TO    CHEMICAL    SCIENCE  123 

owes  many  of  its  most  wonderful  advances,  such,  for 
instance,  as  we  find  in  the  application  of  the  laws  of 
gases  to  substances  in  dilute  solution.  The  extreme 
fluid  elasticity  of  gases  and  vapours  and  their  high 
co -efficient  of  thermal  expansion  render  them 
invaluable  to  the  engineer.  The  nature  of  explosion, 
the  problems  encountered  in  aeronautics,  in  meteoro- 
logy, in  the  study  of  acoustics,  are  all  closely  connected 
with  the  properties,  both  statical  and  dynamical,  of 
substances  in  the  gaseous  state. 

Until  the  middle  of  the  seventeenth  century,  the 
philosophers — students  of  nature — affected  to  despise 
experiment,  their  opinions  being  based  on  observation. 
The  alchemists — seekers  after  the  universal  solvent, 
the  philosopher's  stone  and  the  elixir  of  life — lovers 
as  they  were  of  theory  and  mysticism,  extolled  the 
experimental  method  by  which  they  hoped  to  secure 
wealth  and  the  extension  of  life.  Modern  experi- 
mental science  may  be  considered  as  the  outcome  of 
one  of  the  controversies  between  two  factions  of  the 
former,  combined  with  the  overthrow  of  the  methods 
of  the  latter.  A  discussion  arose  between  the  plenists, 
or  Cartesians,  who  denied  the  possibility  of  a  vacuum, 
and  the  Vacuists,who  maintained  that  there  was  no 
reason  why  a  vacuum  should  not  exist.  Robert 
Boyle,  born  in  1626,  "  son  of  the  Earl  of  Cork,  and 
the  father  of  modern  chemistry,"  flourished  at  the 
time  of  the  plenist  controversy,  and  the  problem 
attracted  him  to  physical  science,  especially  the 
study  of  the  properties  of  air.  In  1658  he  constructed 
the  pneumatical  machine — ah*  pump — which  was 
destined  to  be  of  primary  importance  in  many  of 
his  subsequent  experiments.  His  original  aim  being 
to  obtain  a  vacuum,  he  made  with  its  aid  some 
significant  discoveries.  He  demonstrated  air  pressure, 
and  elucidated  the  volume  pressure  relations  of  gases. 
His  law — viz.,  that,  at  a  constant  temperature,  the 
volume  of  a  given  quantity  of  gas  varies  inversely  as 
the  pressure — was  rediscovered  independently  a  few 
years  later  by  Marriotte,  a  Frenchman.  Boyle's 
speculations  on  the  chemical  nature  of  air,  founded  on 
many  observations,  including  the  gain  in  weight  of 


124  WHAT    INDUSTRY    OWES 

metals  on  calcination,  contributed  to  the  advance  of 
knowledge  in  his  time,  but  the  difficulty  of  pioneer 
work  on  an  invisible  and  almost  intangible  medium 
limited  such  observations  to  the  phenomena  of 
combustion  and  respiration.  In  1661  appeared, 
anonymously,  "  The  Sceptical  Chemist,"  a  book  which 
criticised  the  teaching  of  the  alchemists  and  depre- 
cated their  method  of  expression  and  the  ambiguity 
of  their  doctrines.  As  the  author  of  this  production 
Boyle  did  much  to  sweep  away  the  cobwebs  of 
mysticism.  He  was  an  early  member  of  the 
"  Invisible  College,"  a  body  much  attacked  in  its 
infancy  for  encouraging  the  investigation  of  Nature — 
then  regarded  by  many  as  rank  heresy — which 
eventually  became  our  premier  learned  society,  the 
Royal  Society  of  London.  His  researches  were 
mainly  on  "  air,"  and  there  is  little  doubt  that  he 
prepared  the  gases  now  known  as  hydrogen,  carbon 
dioxide,  and  hydrogen  chloride ;  but  he  did  not 
observe  their  characteristic  properties.  His  work, 
however,  marked  the  beginning  of  a  new  era  in 
natural  philosophy,  his  doctrine  showing  that  scientific 
advances  were  made  not  by  theory  or  practice  alone, 
but  by  the  application  of  both. 

The  discoveries  and  teachings  of  a  genius  have  not 
infrequently  been  overshadowed  by  those  of  a  greater 
and  better -known  contemporary.  This  was  the  case 
with  John  Mayow,  a  medical  practitioner  of  Bath, 
who,  in  his  experiments  on  air  and  his  deductions 
therefrom,  was  ahead  of  the  workers  of  his  time-  He 
recognised  the  existence  of  different  kinds  of  gases  in 
the  air,  and  prepared  a  gas — nitric  oxide — by  the 
action  of  nitric  acid  on  iron.  He  observed  its  action 
on  air,  but  failed  to  see  the  analytical  possibilities  of 
the  discovery.  Boyle  and  Newton  held  the  field  in 
natural  philosophy,  and  Mayow  received  little 
attention.  Stephen  Hales  (1677-1761)  prepared  a 
large  number  of  gases,  but  regarded  them  all  as 
modifications  of  air,  and  failed  to  make  use  of  the 
facts  he  accumulated.  When,  however,  Joseph 
Black  (1728-1799)  discovered  carbon  dioxide,  and 
Daniel  Rutherford  (1749-1819)  isolated  nitrogen,  both 


TO    CHEMICAL    SCIENCE  126 

realised  that  these  gases  were  distinct  in  their  nature 
from  air. 

Then  followed  the  epoch-making  discovery  of 
oxygen  by  Joseph  Priestley  and  Carl  Wilhelm 
Scheele,  a  Swedish  chemist,  working  independently. 
Priestley  also  invented  the  eudiometer.  Henry 
Cavendish  (1731-1810)  made  the  first  analysis  of  air, 
devised  the  electric  spark  method  of  combining 
nitrogen  and  oxygen,  thus  laying  the  foundation  of 
a  very  modern  industry,  and  determined  the  com- 
position of  nitric  acid.  Cavendish  proved  the 
compound  nature  of  water ;  determined  its  quanti- 
titative  composition,  and  also  examined  thoroughly 
the  fixed  air — carbon  dioxide — of  Black. 

All  these  eighteenth  century  investigators  expressed 
their  views  on  the  action  of  air  and  combustion  in 
terms  of  the  phlogistic  theory  of  Becher  and  Stahl, 
and  it  remained  for  Antoine-Laurent  Lavoisier,  the 
French  savant,  who  fell  a  victim  to  the  guillotine  in 
1794,  to  free  them  from  this  incubus  and  to  develop 
the  new  theory  wherein  oxygen  was  assigned  its 
proper  rdle  as  a  constituent  of  air  and  a  supporter  of 
combustion. 

Thus  the  composition  of  air — as  a  mixture  of  oxygen 
and  nitrogen  with  small  quantities  of  carbon  dioxide 
and  water  vapour — and  the  explanation  of  the  nature 
of  combustion  were  gradually  established.  To  these 
early  workers,  and  especially  to  Priestley,  Cavendish, 
and  Lavoisier,  chemical  science  and  industry  owe  an 
irredeemable  debt.  Out  of  chaos  they  produced 
order,  and  paved  the  way  for  the  work  of  Avogadro, 
Clark  Maxwell,  and  Clausius.  No  new  essential 
constituents  of  air  were  discovered  until  the  last 
decade  of  the  nineteenth  century,  when  Rayleigh  and 
Ramsay,  as  an  outcome  of  the  measurements,  by  the 
former,  of  the  density  of  nitrogen  from  various  sources, 
including  atmospheric,  discovered  five  new  chemically 
inert  gases — Argon  (without  energy),  Neon  (new), 
Helium  (Sun),  Krypton  (hidden),  and  Xenon 
(stranger)— no  compounds  containing  these  elements 
being  as  yet  known. 

Hydrogen. — The  discovery  of  hydrogen  is  usually 


126  WHAT    INDUSTRY    OWES 

attributed  to  Paracelsus,  a  Swiss  physician  and 
chemist — fifteenth  to  sixteenth  century.  Its  ex- 
plosive properties  were  known  to  Lemery  about  1700, 
but  it  was  not  until  seventy  or  eighty  years  later 
that  Cavendish  demonstrated  the  individuality 
of  the  gas,  and  showed  its  relation  to  water.  It  is 
prepared  in  the  laboratory  by  the  action  of  a  metal 
such  as  zinc  or  iron  on  dilute  sulphuric  acid,  this  being, 
in  fact,  the  method  by  which  it  was  first  discovered, 
and  it  is  obtained  in  a  much  purer  state,  when  neces- 
sary, by  the  electrolysis  of  barium  hydroxide.  Traces 
of  oxygen  are  removed  by  passage  over  hot  copper 
shavings  or  platinised  asbestos,  the  issuing  gas  being 
dried  by  means  of  calcium  chloride,  or  of  phosphorus 
pentoxide. 

The  properties  of  hydrogen  bear  no  resemblance 
to  those  of  any  other  element.  It  is  colourless, 
odourless,  tasteless,  specifically  lighter  than  any  other 
known  substance,  very  sparingly  soluble  in  water,  and 
capable  of  forming  explosive  mixtures  with  air  or 
oxygen,  with  chlorine  and  fluorine.  It  has  also 
the  property,  in  the  presence  of  finely-divided 
metallic  nickel,  of  combining  with  certain  bodies 
that  are  chemically  unsaturated.  Its  density  is 
less  than  one -fourteenth  that  of  air,  and  its  lightness 
and  buoyancy  render  it  of  great  value  for  use  in 
airships  and  balloons.  Provided  that  it  is  sufficiently 
pure,  the  two  main  advantages  over  coal  gas  for  this 
purpose  are  superior  lifting  power  and  the  absence 
of  deleterious  effect  on  the  material  of  the  envelope. 

As  a  constituent  of  ammonia,  hydrogen  has  in 
recent  years  been  largely  used  in  Germany  in  a  process 
for  the  fixation  of  nitrogen,  whereby  the  combination 
of  the  two  gases,  under  high  pressure — up  to  200 
atmospheres — at  a  temperature  of  500  deg.  Gent., 
is  effected  by  the  action  of  certain  catalytic  agents, 
such  as  osmium,  uranium,  iron,  manganese,  or 
tungsten.  The  efficiency  of  the  catalysts  is  enhanced 
by  certain  compounds  of  the  alkali  or  alkaline  earth 
metals  ;  but  catalyst  "  poisons  "  also  exist,  and  these 
are  many  and  various.  The  gases  must  be  freed 
from  these  substances,  the  most  obnoxious  of  which 


TO    CHEMICAL    SCIENCE  127 

are  compounds  of  sulphur  and  the  hydrides  of  arsenic 
and  phosphorus.  The  ammonia  is  separated  by 
liquefaction,  produced  by  strong  cooling,  or,  in 
certain  cases,  by  solution  in  water.  This  process 
was  devised  by  Haber,  is  worked  by  the  Badische 
Anilin  und  Soda  Fabrik,  and  promises  to  become 
one  of  the  chief  methods  of  producing  nitrogen.  It 
need  not  stop  at  this  stage,  however,  for  through  the 
work  of  Ostwald  a  mixture  of  air  and  ammonia  gas, 
under  proper  conditions,  with  platinum,  as  catalyst, 
yields  nitric  acid,  and  the  process  may  be  developed 
by  proper  regulation  to  yield  ammonium  nitrate,  a 
substance  of  high  value  as  a  fertiliser. 

The  third  important  use  of  hydrogen  is,  as  we  have 
observed  in  a  previous  article,  in  the  hardening  of 
fats,  by  direct  action  in  the  presence  of  finely-divided 
metallic  nickel.  According  to  the  method  of  Sabatier 
and  Senderens  certain  fine  chemicals  are  now  made  by 
the  nickel  method  of  hydrogenation,  and  this  also 
is  likely  to  find  extended  application  in  industry. 

With  these  developments  it  has  become  necessary 
to  find  means  of  producing  hydrogen  in  large  quan- 
tities at  low  cost.  Owing  to  the  expense  of  raw 
materials,  and  the  difficulty  of  securing  a  convenient 
cycle  of  operations  whereby  the  starting  materials 
may  be  recovered,  production  by  the  action  of  metals 
on  acids  is  not  to  much  extent  carried  out  on  the 
works  scale,  though  the  method  may  occasionally 
be  used  for  military  purposes.  Many  patents  have 
been  taken  out  for  the  manufacture,  and  we  will 
refer  to  some  of  the  more  important  of  them : — 
(1)  By  the  action  of  steam  on  red  hot  iron,  iron 
oxide  is  formed,  and  hydrogen  is  set  free.  It  is 
then  purified  from  dust,  sulphur  compounds,  carbon 
dioxide,  &c.,  by  suitable  scrubbing  treatment. 
The  iron  oxide  is  reduced  when  necessary  by  replacing 
the  current  of  steam  by  one  of  water-gas,  the  residue 
from  this  reaction  being  a  source  of  nitrogen — 
Messerschmitt  process.  (2)  By  freeing  water-gas 
from  carbon  dioxide,  by  means  of  lime  or  caustic 
soda,  and  subjecting  the  residue  to  the  extreme  cold 
produced  by  boiling  liquid  air,  nitrogen  and  carbon 


128  WHAT    INDUSTRY   OWES 

monoxide  are  liquefied,  leaving  the  hydrogen  in  the 
gaseous  state — Linde-Frank-Caro  process.  (3)  By 
the  electrolysis  of  the  chloride  or  hydroxide  of  an 
alkali.  (4)  The  decomposition  of  acetylene — prepared 
from  calcium  carbide  and  water — by  heating 
electrically.  Hydrogen  is  prepared  for  Zeppelins 
by  this  method,  which  yields  also  a  valuable  by- 
product in  the  form  of  fine  lampblack.  (5)  The  gas 
is  also  produced  by  a  number  of  other  patent  methods, 
mainly  useful  for  military  purposes.  Hydrolith  is 
calcium  hydride,  prepared  by  the  action  of  hydrogen 
on  calcium  in  the  electric  furnace,  and  on  contact 
with  water,  yields  double  the  volume  of  hydrogen 
originally  expended  in  preparing  it.  Hydrogenite 
is  a  mixture  of  five  parts  of  ferrosilicon,  four  parts  of 
slaked  lime,  and  twelve  parts  of  caustic  soda.  When 
heated  locally  a  reaction  takes  place,  and  spreads 
throughout  the  mass  with  evolution  of  hydrogen. 
Both  of  these  processes  are  due  to  Jaubert. 

Oxygen,  discovered  by  Priestley  and  Scheele,  and 
named  by  Lavoisier,  occupies  about  one-fifth  of 
the  volume  of  the  atmosphere,  and  its  properties  as 
a  supporter  of  life  and  combiistion  render  it  one  of 
the  most  important  of  the  elements.  It  is  also  the 
most  abundant,  representing  about  half  the  weight 
of  the  solid  crust  of  the  earth,  and  roughly  eight- 
ninths  of  the  water.  It  can  be  prepared  in  the  labora- 
tory by  heating  chlorate  of  potash  either  alone  or 
with  manganese  dioxide,  by  the  action  of  sulphuric 
acid  on  bichromates  or  permanganates,  or  by  the 
electrolysis  of  dilute  sulphuric  acid,  or  of  solutions 
of  alkalies.  On  a  commercial  scale,  Brin's  process  of 
heating  barium  monoxide — the  analogue  of  lime — 
in  dry,  purified  air  to  about  700  deg.  Cent,  under 
10  Ib.  pressure,  for  long  held  the  field.  The  oxide 
takes  up  oxygen,  forming  barium  peroxide ;  the 
nitrogen  is  then  pumped  off,  pressure  being  reduced 
to  about  2  Ib.  Under  these  conditions  the  peroxide 
gives  up  its  excess  of  oxygen,  which  in  turn  is  pumped 
off  and  compressed  into  cylinders,  reforming  the 
monoxide,  which  is  available  again  for  the  same  cycle 
of  changes.  The  method,  however,  has  now  been 


TO    CHEMICAL    SCIENCE  120 

largely  replaced  by  the  liquid  air  process,  which 
depends  for  its  utility  on  the  ease  with  which  air  can 
bo  liquefied  by  the  method  of  self-intensive  cooling 
introduced  on  the  Continent  by  Linde  and  into 
England  by  Hampson.  Advantage  is  taken  of  the 
fact  that  a  compressed  gas  cools  on  expansion.  Air 
is  compressed  through  a  spiral,  and  allowed  to  escape 
from  a  jet.  On  issuing  it  is  cooled,  and  in  turn 
cools  the  air  in  the  spiral  by  external  contact.  Thus 
the  issuing  gas  becomes  increasingly  colder,  until 
finally  it  issues  from  the  jet  in  the  liquid  form.  Liquid 
oxygen  and  liquid  nitrogen  boil  at  different  tempera- 
tures, so  that  if  the  liquid  air  is  fractionated  the  two 
gases  can  be  obtained  in  a  fair  state  of  purity. 

Oxygen  finds  application  in  medicine,  in  the 
chemical  laboratory,  and  in  the  production  of  high 
temperatures,  such  as  are  obtained  by  feeding 
acetylene,  hydrogen,  and  coal  gas  flames  with  the 
gas.  Oxy-acetylene  cutting  and  welding,  oxy- 
hydrogen  melting,  including  platinum  working,  the 
autogenous  soldering  of  lead,  and  the  use  of  lime- 
light, all  depend  on  the  production  of  an  intensely  hot 
oxygen -fed  flame. 

Ozone  is  a  colourless  gas,  condensable  in  liquid  air 
to  a  deep  blue  unstable  liquid.  Van  Marum,  in  1785, 
and  Schonbein,  in  1840,  observed  a  peculiar  smell 
in  the  neighbourhood  of  electrical  machines  in 
motion,  and  the  latter  found  that  it  was  due  to  a 
gas,  which  he  named  and  found  other  means  of 
producing.  Andrews,  in  1856,  showed  that  the 
gas  contained  oxygen  only,  and  Soret,  in  1866,  proved 
its  composition,  which  is  represented  by  the  formula 
O3.  It  is  prepared  by  the  action  of  a  silent  electric 
discharge  on  air  or  oxygen,  a  current  of  which  is 
passed  through  a  special  apparatus  called  an  ozoniser. 
The  first  of  these  was  devised  by  Siemens  in  1857, 
and  since  that  date  numerous  patents,  founded 
much  on  the  same  principle,  have  been  recorded. 

The  commercial  preparation  resembles  that  on 
the  small  scale.  The  pure  substance  is  not  obtained 
in  either  case ;  not  more  than  25  per  cent,  of  the 
oxygen  is  transformed  into  ozone  under  the  best 


130  WHAT    INDUSTRY   OWES 

conditions.  The  product  is  used  in  the  sterilisation 
of  water  and  to  a  less  extent  of  certain  foods. 

Acetylene  was  discovered  in  1836  by  Edmund  Davy, 
Professor  at  the  Royal  Dublin  Society,  during  an 
attempt  to  isolate  potassium  by  heating  calcined 
tartar  with  carbon.  He  obtained  a  black  mass, 
which  in  contact  with  water  gave  rise  to  an  inflam- 
mable gas,  and  he  suggested  that  if  a  cheap  method 
could  be  found  for  preparing  it,  the  gas  might  well 
be  used  as  an  illuminant.  Its  development  as  an 
industrial  commodity  was  not  realised  until  over  fifty 
years  later,  but  in  the  meantime  several  famous 
names  came  into  the  literature  of  the  subject,  includ- 
ing Hare,  Berthelot,  Wohler,  Kekule,  Vohl,  and  Sir 
James  Dewar.  Hare  unknowingly  made  calcium 
carbide,  and  from  it  acetylene,  by  the  action  of 
water.  Berthelot  prepared  metallic  acetylides,  and 
produced  acetylene  electrically  from  methane  and 
also  from  carbon  and  hydrogen.  Wohler  made 
calcium  carbide  by  heating  an  alloy  of  zinc  and 
calcium  to  a  high  temperature  with  carbon.  Kekule 
prepared  acetylene  by  the  electrolysis  of  the  salts  of 
dibasic  unsaturated  organic  acids.  Vohl  obtained 
the  gas  by  passing  oils  through  red  hot  tubes,  thereby 
laying  the  foundation  of  our  modern  oil-cracking 
processes.  From  American  petroleum  he  obtained 
a  gas  containing  20  per  cent,  of  acetylene.  Dewar 
obtained  acetylene  by  passing  hydrogen  through 
tubes  made  of  retort  carbon  heated  to  whiteness  by 
means  of  an  electric  current. 

Acetylene  is  used,  as  we  have  already  mentioned, 
in  one  of  the  processes  for  making  hydrogen  ;  as 
an  illuminant  in  isolated  dwellings,  and  in  motor 
and  bicycle  lamps.  It  is  invariably  prepared  by 
the  action  of  water  on  calcium  carbide,  which  comes 
on  the  market  in  the  form  of  grey  lumps,  the  product 
of  heating  lime  with  carbon  in  the  electric  furnace. 
The  gas  owes  its  position  as  an  industrial  product  to 
the  development  of  the  electric  furnace  by  Siemens, 
Bradbury,  Oowles,  and  Moissan ;  but  the  credit 
for  the  realisation  of  the  possibility  of  producing 
calcium  carbide  on  a  commercial  scale  belongs  to 


TO    CHEMICAL    SCIENCE  131 

Willson,  an  American.  In  1886,  Cowles  introduced 
a  furnace  lining  consisting  of  a  mixture  of  lime  and 
carbon,  and  produced  calcium  carbide  by  the  acci- 
dental overheating  of  this  lining.  No  attempt  was 
then  made  to  utilise  the  discovery  ;  but,  in  1892, 
Willson,  while  working  at  Spray,  with  the  object 
of  reducing  lime  to  obtain  calcium  for  the  reduction 
of  alumina,  prepared  large  quantities  of  the  carbide, 
and,  realising  the  potentialities  of  the  substance,  set 
up  a  works  for  its  production. 

Nitrogen,  which  forms  about  four-fifths  of  the  air, 
is  produced  by  the  methods  we  have  already  indi- 
cated,* especially  the  Linde-Hampson  process,  and 
is  used  in  the  synthetic  preparation  of  ammonia,  and 
of  cyanamido  and  cyanides,  from  calcium  and 
barium  carbides  respectively. 

Chlorine,  discovered  by  Scheele  in  1774,  and  pro- 
nounced an  element  by  Davy  in  1810,  is  a  heavy 
yellow  poisonous  gas  of  an  extremely  irritating 
odour.  It  is  largely  used  in  the  sterilisation  of  water 
and  in  gold  extraction,  and  has  been  employed  as 
poison  gas  during  the  war.  It  is  prepared  by  the 
action  of  manganese  dioxide  on  hydrochloric  acid, 
the  oxide  being  recovered  by  the  Weldon  process. 
It  may  be  converted  into  bleaching  powder,  through 
its  absorption  by  lime,  or  liquefied  by  cold  and  pres- 
sure and  stored  in  steel  cylinders. 

Carbon  Dioxide,  or  carbonic  acid  gas,  a  waste 
product  of  the  brewery,  is  used  for  aerating  beer  and 
mineral  waters,  and  is  sometimes  employed  as  a 
freezing  agent. 

Carbonyl  Chloride,  or  phosgene,  prepared  by  the 
interaction  of  chlorine  and  carbon  monoxide  in  the 
presence  of  animal  charcoal,  or  of  antimony  penta- 
chloride,  or  by  the  action  of  fuming  sulphuric  acid 
on  carbon  tetrachloride,  is  used  in  the  manufacture 
of  dyes,  and  has  also  been  employed  as  a  poison  gas. 

Laughing  Gas,  or  nitrous  oxide,  is  made  by  heating 
ammonium  nitrate.  It  was  discovered  by  Priestley 
in  1772,  and  is  used  as  an  anaesthetic  in  dentistry. 

*  Refer  to  Agriculture  and  Hydrogen. 


132  WHAT    INDUSTRY    OWES 

We  do  not  need  to  dilate  on  the  relation  between 
science  and  these  products  which  are  so  obviously 
scientific  in  their  conception,  elucidation  and  deve- 
lopment 


TO    CHEMICAL    SCIENCE  133 


CHAPTER  XIX. 
GOVERNMENT  CHEMISTRY. 

IN  the  article  dealing  with  Agriculture  and  Food, 
we  have  referred  to  the  official  agricultural  analysts 
and  public  analysts,  who  are  appointed  under  statutes 
to  safeguard  the  quality  of  supplies  of  fertilisers  and 
feeding  stuffs,  food  and  drugs  ;  and  we  will  now  refer 
to  other  official  chemists  directly  or  indirectly 
concerned  with  industry. 

In  1843  a  laboratory  was  established  at  Somerset 
House,  in  connection  with  the  Inland  Revenue 
Department,  to  check  adulteration  of  tobacco,  and 
later  a  second  laboratory  was  established  at  the 
Custom  House  for  the  examination  of  wines,  spirits, 
and  other  imported  articles  liable  to  duty.  In  1894 
the  control  of  these  laboratories  was  entrusted  to 
one  Principal,  and  in  1897  the  Excise  Branch  was 
transferred  to  a  new  building  at  Clement's  Inn -passage. 
In  1911  the  Government  Laboratory  was  constituted 
an  independent  department  under  the  Treasury,  with 
a  separate  Parliamentary  Vote,  entitled  "  Government 
Chemist."  The  Laboratory  undertakes  investiga- 
tions for  every  other  Government  Department,  the 
greater  part  being  carried  out  at  Clement's  Inn- 
passage,  and  in  the  branch  laboratory  at  the  Custom 
House.  The  Government  Chemist  also  controls 
eighteen  stations  in  different  parts  of  the  United 
Kingdom,  where  tests  are  made  for  revenue  purposes. 
From  a  recent  report,  we  gather  that  the  work  for  the 
Department  of  Customs  and  Excise  relates,  mainly, 
to  the  assessment  of  duty  and  drawback,  and  to  regula- 
tions and  licences,  in  connect/ion  with  the  manufacture 
and  sale  of  dutiable  articles,  such  as  beer,  spirits, 
wine,  tobacco,  tea,  sugar,  coffee,  cocoa,  and  prepara- 
tions advertised  for  the  cure  or  relief  of  human 

K  2 


134  WHAT    INDUSTRY   OWES 

ailments — commonly  called  "  patent  medicines." 
The  work  for  the  Admiralty  includes  the  examination 
of  food  substances,  the  analysis  of  metals  and  of 
contract  stores  ;  that  for  the  Board  of  Agriculture 
and  Fisheries  refers  largely  to  imported  dairy  produce 
and  margarine,  and  includes — for  the  Fisheries 
Division — samples  of  river  water  believed  to  have 
been  polluted  and  to  have  caused  injury  to  fish,  as 
well  as  the  determination  of  the  salinities  of  samples 
of  sea  water  for  the  Permanent  International  Council 
for  Exploration  of  the  Sea.  Samples  of  beer  and 
whiskey  are  examined  for  the  Central  Control  Board 
(Liquor  Traffic) ;  and  of  drugs,  pharmaceuticals 
and  contract  supplies  for  the  Ciown  Agents  for  the 
Colonies.  Fire-clay  and  limestone  from  various 
districts  are  examined  for  the  Geological  Survey  ; 
lead  glazes  and  enamels  for  the  Home-office  ;  drugs 
for  the  India-office,  and  stamps  and  inks  ior  the 
Board  of  Inland  Revenue.  Investigations  on  pre- 
servatives in  food  are  carried  out  for  the  Local 
Government  Board  ;  and  on  paper,  pigments,  gum, 
engineering  and  general  stores  for  the  Post-office  ; 
ink  and  typewriter  ribbons  for  the  Stationery-office  ; 
lighthouse  stores  for  the  Corporation  of  Trinity 
House  ;  lime  and  lemon  juice  and  ship's  stores  for  the 
Board  of  Trade  ;  food  supplies  for  the  Army,  drugs 
and  surgical  dressings,  for  the  Army  Medical  Depart- 
ment, for  the  War-office  ;  samples  of  varied  character 
for  the  War  Trade  Department ;  samples  of  water  for 
the  Office  of  Woods  and  Forests  ;  of  contractors' 
supplies  and  of  water  for  the  Offices  of  Works — 
London  and  Dublin  ;  and  samples  referred  by  the 
magistrates  under  the  Sale  of  Food  and  Drugs  Acts, 
1875  and  1899,  and  submitted  by  the  Board  of 
Agriculture,  under  the  Fertilisers  and  Feeding  Stuffs 
Act.  The  total  number  of  samples  examined  during 
the  year  ended  March  31st,  1916,  was  383,892.  The 
work  has  obviously  an  important  bearing  on  industry 
and  commerce,  and  entails  the  employment  of  a 
large  technical  staff,  of  which  many  members  are 
required  to  be  highly  trained  and  competent  chemists. 
As  illustrating  the  value  of  their  work,  we  may  refer 


TO    CHEMICAL    SCIENCE  135 

to  the  examination  of  food  for  the  armies  in  the  field 
during  the  war,  work  essential  in  the  interests  both 
of  the  health  of  the  troops  and  of  the  Exchequer. 
The  food  must  be  wholesome  ;  but  the  findings  of  the 
chemists  will  determine  the  cash  value  of  the  supplies  : 
a  deviation  of,  say,  1  or  2  per  cent,  of  moisture  in 
flour,  biscuits  or  margarine,  may  involve  a  reduction 
of  hundreds  of  pounds  on  a  single  contract. 

Although  the  Government  Laboratory  constantly 
advises  other  departments,  some  possess  their  own 
laboratories  for  special  purposes.  The  Admiralty  has 
a  staff  under  the  Admiralty  Chemist,  and  einploys 
chemists  in  connection  with  the  examination  of 
various  materials  of  construction  and  victualling 
stores.  The  Admiralty  has  also  its  duly  appointed 
Adviser  on  Petroleum,  as  well  as  officers  .possessing 
special  scientific  experience,  and  professors  of 
chemistry  in  the  Royal  Naval  Colleges.  The  War- 
office,  too,  makes  good  use  of  chemists,  in  many 
matters  arising  out  of  the  conditions  of  modern  war- 
fare, and  instruction  in  chemistry  is  given  »m  the 
Royal  Ordnance  College,  the  Royal  Army  Medical 
College,  the  Royal  Military  Academy,  and  other 
establishments.  Under  the  Ministry  of  Munitions, 
in  addition  to  chemists  engaged  in  an  advisory  capa- 
city, there  are  considerable  numbers  in  charge  of  the 
production  of  explosives  in  Government  and  con- 
trolled factories,  and  special  staffs  are  appointed 
for  research  and  inspection  work. 

Official  analysts  are  appointed  to  the  Home -office 
for  toxicological  work,  as  well  as  in  connection  with 
the  Explosives  Department  and  the  Factory  Depart- 
ment. The  Local  Government  Board  possesses  a 
Department  for  the  inspection  of  food  and  a  staff  of 
specially  qualified  inspectors  to  assist  in  the  adminis- 
tration of  the  Alkali,  &c.,  Works  Regulation  Act. 
The  Metropolitan  Water  Board  and  the  Rivers  Boards 
in  various  parts  of  the  country  have  their  chemical 
and  bacteriological  laboratories,  and  so  have  the 
Sewage  Boards  and  Works.  The  Scottish  Office  also 
appoints  inspectors  under  the  Alkali  Act  and  Rivers 
Pollution  Prevention  Act. 


136  WHAT    INDUSTRY   OWES 

The  London  County  Council  controls  a  consider- 
able staff  for  chemical  investigations,  including  gas 
testing,  and  the  Board  of  Trade  appoints  the  Gas 
Referees,  in  accordance  with  the  Metropolis  Gas 
Acts,  to  prescribe  the  apparatus  and  materials 
to  be  employed  for  testing  the  illuminating  power, 
calorific  power,  purity  and  pressure  of  the  gas, 
the  mode  of  testing,  and,  in  certain  cases,  the  times 
of  testing,  the  current  prescriptions  being  published 
in  the  "  Notification  of  Gas  Referees."  Other  county 
and  borough  authorities  make  provision  for  the  inspec- 
tion of  water  and  gas  supplies.  Chemists  are  also 
included  in  the  staff  of  the  Patent-office,  and  Assayers 
render  responsible  service  in  the  Royal  Mint  and 
at  the  Assay  Offices,  as  well  as  for  the  Bank  of 
England. 

The  Scientific  and  Technical  Department  of  the 
Imperial  Institute  conducts  investigations  for  the 
Indian  and  Colonial  Government.0,  chiefly  relating  to 
the  composition  and  utilisation  of  raw  materials. 
The  National  Physical  Laboratory  includes  a  Depart- 
ment of  Metallurgy  and  Metallurgical  Chemistry. 
Laboratories  are  attached  to  many  public  Institu- 
tions, such  as  the  Davy-Faraday  Research  Laboratory 
of  the  Royal  Institution,  and  those  of  the  Lister 
Institute  and  the  Royal  Dublin  Society. 

The  existence  of  this  extent  of  official  organisation 
in  chemistry  is  little  known  to  the  general  public, 
but  it  is  obviously  indispensable  to  the  well-being 
of  the  community.  The  personnel  of  our  chemical 
service  includes  many  men  of  science  of  high  repute 
in  their  professions  who  deserve  well  of  their  country, 
and  it  is  essential  that  the  conditions  attaching  to 
this  service  should  be  such  that  it  will  continue  to 
attract  chemists  of  the  highest  competence.  We  have 
endeavoured  to  make  this  list  fairly  comprehensive, 
but  have  not  referred  to  India  and  the  Overseas 
Dominions,  where  many  chemists  hold  appointments 
analogous  to  those  we  have  indicated  ;  nor  have  we 
referred  to  the  valuable  work  carried  out  by  analysts 
in  hospitals  and  public  health  laboratories,  or  the 
appointments  held  in  the  Universities  and  Technical 


TO    CHEMICAL    SCIENCE  137 

Colleges,  to  which  we  look  for  the  continued  supply 
of  lieutenants  to  meet  our  requirements  in  the  various 
branches  of  chemical  practice. 


138  WHAT    INDUSTRY    OWES 


CONCLUSION. 

WHILE  we  have  confined  our  attention  mainly  to 
the  debts  of  industry  to  chemical  science,  we  do  not 
suggest  that  those  due  to  physical  and  mechanical 
science  should  not  be  similarly  acknowledged. 

The  art  of  engineering  has  been  steadily  built  up 
through  the  ages,  but  modern  developments  are, 
in  the  main,  directly  attributable  to  the  advance 
of  science.  In  chemical  industries,  however,  the 
processes  of  manufacture,  in  many  cases,  preceded 
the  discovery  of  the  scientific  principles  on  which  they 
were  based.  The  ironmaster,  the  dyer,  the  soap 
and  candle  maker,  the  tanner,  the  potter,  and  the 
glass  manufacturer,  were  in  existence  centuries 
before  serious  attention  was  paid  to  the  science  under- 
lying their  work.  Conventions  die  hard,  and  for 
a  long  time  there  was  little  enthusiasm  to  take  advan- 
tage of  what  science  had  to  offer.  It  is  freely  admitted 
that  the  state  of  civilisation  attained  before  the  advent 
of  modern  science  was  far  removed  from  the  conditions 
of  life  of  primitive  man  ;  but  it  is  claimed  that 
while  science  was  so  little  developed,  industry  had 
to  look  to  experience  as  the  only  basis  to  work  upon. 
Experience,  accumulated  slowly  and  at  great  cost, 
had  done  great  things  ;  but  the  rate  of  progress 
in  industry  developed  in  the  past  century  defies 
comparison  with  all  the  centuries  combined  since 
time  was — so  far  as  we  know  !  Still,  let  us  admit  that 
the  inheritance  was  great,  and  that  even  the  alchemist 
preserved  much  that  was  good  in  chemistry,  just 
as  the  monks  of  the  Middle  Ages  preserved  much 
that  was  good  in  classical  literature  and  architecture. 
We  have  endeavoured  to  indicate  the  interdependence 
of  science  and  industry  on  one  another,  and  to  show 
how  frequently  science — "  the  nursling  of  interest 
and  the  daughter  of  curiosity  " — pursued  for  her 


TO    CHEMICAL    SCIENCE  139 

own  sake,  has  sooner  or  later  proved  her  practical 
utility.  Incidentally  we  have  shown  that  though 
"  Genius  is  of  no  country,"  British  men  of  science, 
often  in  the  face  of  small  encouragement,  have  played 
their  part  in  industrial  development.  There  is 
no  reason  to  depreciate  the  value  of  their  work,  or  to 
pay  much  attention  to  the  Jeremiahs  who  seem  to 
delight  in  bemoaning  the  industrial  and  commercial 
position  of  this  country  but  are  seldom  able  to  offer 
any  constructive  criticism. 

Advancement  may  be  the  outcome  of  the  labours  of 
the  consultant,  the  chemist  on  the  works,  the  official 
chemist,  or  the  professor  ;  all  have  contributed  their 
share  to  discovery  and  invention.  In  any  case,  it  is 
certain  that  our  industries  have  utilised  their  know- 
ledge, skill  and  experience  to  a  greater  extent  than 
has  been  generally  recognised  ;  otherwise  much  that 
has  been  done  in  the  last  three  years  would  have  been 
impossible,  and  our  position  would  have  been  far  worse 
than  It  is. 

We  feel  that  the  apathy  towards  science  prevailing 
before  the  war  was  more  imaginary  than  real  and, 
such  as  it  was,  is  being  overcome  ;  that  the  general 
public  is  beginning  to  realise  something  of  the 
importance  of  science  in  the  affairs  of  everyday  life, 
and  that  the  time  is  at  hand  when  the  services  of 
the  man  of  science  will  be  better  understood  and 
consequently  more  substantially  rewarded.  The 
men  of  science  themselves  are  increasing  in  number 
and  influence  ;  their  work  lies  more  and  more  in  the 
control  of  large  scale  operations,  as  well  as  in  the 
laboratory.  The  time  has  passed  when  men  feared 
to  probe  into  the  truth  as  if  it  were  sacrilege,  or  to 
imagine  things  beyond  certain  knowledge  and  estab- 
lished fact,  or  to  explore  into  realms  of  not  only  the 
improbable  but  the  seemingly  impossible,  whence  so 
much,  with  the  aid  of  science,  has  been  and  is  yet  to 
be  derived. 

To-day,  the  arts  and  sciences  go  hand  in  hand : 
the  engineer  and  the  chemist,  each  recognising  the 
limits  of  his  own  domain,  though  the  line  dividing  them 
may  often  be  difficult  to  define,  co-operate  with  one 


140  WHAT    INDUSTRY    OWES 

another  and  mutually  assist  in  the  solution  of  indus- 
trial problems.  Now  is  the  time  for  leaders  of  indus- 
try to  see  to  it  that  the  opportunity  is  taken  of  making 
good,  wherever  possible,  the  connecting  link  between 
science  and  practice.  A  thorough  overhauling  of 
n  ethods  and  plant  should  keep  our  consulting 
chemists  and  engineers  well  employed  in  preparation 
for  the  future.  There  is  no  lack  of  good  men,  and 
soon  there  will  be  enough  and  to  spare  for  permanent 
appointments  on  the  works. 

If  in  these  articles  we  have  been  successful  in 
indicating  some  of  the  triumphs  of  science  in  industry, 
and  if  our  efforts  have  in  any  way  conduced  to  a  better 
realisation  of  the  value  of  scientific  thought  and 
method,  we  may  rest  satisfied  that  our  labour  has  not 
been  in  vain. 


TO    CHEMICAL    SCIENCE  141 


BIBLIOGRAPHY. 


BACON  and  HAMOR.  The  American  Petroleum  Industry. 
New  York,  1916. 

BAKER,  J.  L.     The  Brewing  Industry.     London,  1905. 

BLOUNT,  B.  Cement.  Lecture,  Institute  of  Chemistry, 
London,  1912. 

BLOUNT  and  BLOXAM.  Chemistry  for  Engineers  and 
Manufacturers.  London,  1910-1911. 

BLOXAM,  C.  L.  Chemistry,  Inorganic  and  Organic. 
Edited  by  A.  G.  Bloxam  and  S.  Judd  Lewis.  London,  1913. 

BORCHERS,  W.  Electric  Smelting  and  Refining.  London, 
1904. 

BORCHERS,  W.  Metallurgy.  Translated  by  W.  T. 
Hall  and  C.  R.  Hayward.  London  and  New  York,  1911. 

BROWN,  J.  CAMPBELL.  History  of  Chemistry  from  the 
Earliest  Times  to  the  Present  Day.  London,  1913. 

BURGESS  and  LE  CHATELIER.  The  Measurement  of 
High  Temperatures.  New  York,  1912. 

BUTTERFIELD,  W.  J.  A.  Chemistry  in  Gas  Works. 
Lecfure,  Institute  of  Chemistry.  London,  1913. 

BYROM  and  CHRISTOPHER.  Modern  Coking  Practice. 
London,  1910. 

CAIN  and  THORPE.  The  Synthetic  Dyestuffs  and  the 
Intermediate  Products  from  which  they  are  derived.  London, 
1917. 

CHAPMAN,   A.    CH ASTON.     Brewing.     Cambridge,    1912. 

CROSS,  C.  F.  Cellulose.  Lecture,  Institute  of  Chemistry. 
London,  1912. 

CROSS  and  BEVAN.  Researches  on  Cellulose,  1895/1910. 
London,  1901-1912. 

A  Text-book  of  Papermaking.     London,  1907. 

DREAPER,  W.  P.  The  Research  Chemist  in  the  Works 
with  Special  Reference  to  the  Textile  Industry.  Lecture, 
Institute  of  Chemistry.  London,  1914. 

ENGLER  and  HOFER.     Das  Erdol.     Leipzig,  1909 -f. 

FINDLAY,  ALEXANDER.  Chemistry  in  the  Service  of 
Man.  London,  1917. 

HARBORD  and  HALL.  The  Metallurgy  of  Steel.  London, 
1916. 


142  WHAT    INDUSTRY    OWES 

HERRICK,  R.  F.  Denatured  or  Industrial  Alcohol.  New 
York,  1907. 

HILDITCH,  T.  P.  A  Concise  History  of  Chemistry. 
London,  1911. 

HILL,  C.  A.  The  Function  and  Scope  of  the  Chemist  in 
a  Pharmaceutical  Works.  Lecture,  Institute  of  Chemistry. 
London,  1913. 

LAFAR,    FRANZ.     Technical  Mycology.     London,    1910. 

LEEDS  and  BUTTERFIELD.     Acetylene.     London,   1910. 

LEWKOWITSCH,  J.  Chemical  Technology  of  Oils,  Fats 
and  Waxes  London,  1913-1915. 

Loins,  HENRY.  The  Dressing  of  Minerals.  London, 
1909. 

LUNGE,  GEORGE.  Coal  Tar  and  Ammonia.  London, 
1916. 

Sulphuric  Acid  and  Alkali.     London,  1911. 

MACNAB,  WILLIAM.  Explosives.  Lecture,  Institute  of 
Chemistry.  London,  1914. 

MCMILLAN,  W.  G.  A  Treatise  on  Electro -Metallurgy. 
London,  1899. 

MARSHALL,   ARTHUR.     Explosives.     London,    1917. 

MELLOR,  J.  W.  Treatise  on  Quantitative  Inorganic 
Analysis.  London,  1913. 

MEYER,  ERNST  VON.  A  History  of  Chemistry  from 
Earliest  Times  to  the  Present  Day.  Translated  by  George 
McGowan.  London,  1906. 

MIERS,  Sir  H.  A.     Mineralogy.     London,  1902. 

NEWLANDS,  B.  E.  R.     Sugar.     London,  1913. 

PORRITT,  B.  D.  The  Chemistry  of  Rubber.  London, 
1913. 

PRICE,  T.  SLATER.  Per-acids  and  their  Salts.  London, 
1912. 

PROCTER,  H.  R.  The  Principles  of  Leather  Manufacture. 
London,  1903. 

RAMSAY,  SIR  WILLIAM.  The  Gases  of  the  Atmosphere, 
the  History  of  their  Discovery.  London,  1915. 

REDWOOD,  Sir  BOVERTON,  Bart.  Petroleum.  London, 
1913. 

ROBERTS- AUSTEN,  Sir  W.  C.  Introduction  to  the  Study  of 
Metallurgy.  London,  1910. 

ROSCOE  (Sir  H.  E.)  and  SCHORLEMMER.  Treatise  on 
Chemistry.  London,  1911-1913. 

ROSE,  Sir  T.  KIRKE.  The  Metallurgy  of  Gold.  London, 
1915. 

STANSFIELD,  ALFRED.  The  Electric  Furnace.  New 
York,  1907. 


TO    CHEMICAL    SCIENCE  143 

TERRY,  HUBERT  L.  India-rubber  and  its  Manufacture. 
London,  1907. 

THORPE,    Sir    EDWARD.       A    Dictionary    of    Applied 
Chemistry.     London,  1912.  • 
History  of  Chemistry.     London,  1909-10. 

TILDEN,  Sir  WILLIAM  A.  Chemical  Discovery  and 
Invention  in  the,  Twentieth  Century.  London,  1916. 

TROTMAN,  S.  R.  Leather  Trades  Chemistry.  London, 
1908. 

TURNER,  T.     The  Metallurgy  of  Iron.     London,  1915. 

WHITE,  EDMUND.  Thorium.  Lecture,  Institute  of 
Chemistry.  London,  1912. 

WOOD,  JOSEPH  TURNEY.  The  Puering,  Bating,  and 
Drenching  of  Skins.  London,  1912. 

WRIGHT,  S.  B.  A  Practical  Handbook  on  the  Distillation 
of  Alcohol  from  Farm  Products,  and  De-naturing.  New 
York,  1907. 


144 


WHAT    INDUSTRY    OWES 


IN  DEX. 


ABBE,  71 

Abel,  46 

Acetic  Acid,  81 

Acetone,  86 

Acetylene,  130 

Acetylsalicylic  Anhydride,  89 

Achard,  20,  101 

Acheson,  67,  69 

Acids,  80 

Agriculture,  95 

Alcohol,  84,  109 

,  Absolute,  110 

,  Denaturing  of,  110 

Alizarin,  43 

Alkali  Act,  30 

Manufacture,  27 

,  Manufacture  by  Elec- 
trolysis, 32 

Waste,  29 

Alum-tan,  61 

Aluminium,  15 

Alundum,  69 

Ammonal,  47 

Ammonia,  37 

Gas,  103 

Ammonia -soda  Process,  31 

Ammoniacal  Copper  Solution. 
84 

Ammonium  Salts,  83 

Sulphate,  23 

Anaesthetics,  85 

,  Local,  89 

Analytical  Re-agents,  87 

Andrews,  129 

Aniline,  44 

Anthracene,  40 

Antifebrin,  89 

Antimony  Salts,  84 


Antipyretics,  89 
Antiseptics,  89 
Archer,  91 
Arsenic  Acid,  81 

,  Organic  Compounds  of, 

89 

Aspirin,  81,  88 
Astatki,  55 
Atoxyl,  89 
Atropine,  88 


BACON,  Roger,  45 
Bactericidal  Agents,  89 
Barium,  Peroxide,  83 

Salts,  83 

Bases,  81 
Basic  Slag,  98 
Beer,  104 
Benzene,  39 
Benzine,  54 
Benzoic  Acid,  81 
Bernard  Freres,  16 
Berthelot,  130 
Berzelius,  17 
Bessemer,  3 
Bevan,  52 

Bieberich  Scarlet,  42,  43 
Birkeland  and  Eyde,  97 
Bismuth  Salts,  84 
Black,  124 
Blacking,  121 
Black  Lead,  121 
Blast       Furnaces,       Water- 
jacketed,  10 
Blasting  Gelatine,  47 
Bleaching  Powder,  30 
Blue  Prints,  93 


TO    CHEMICAL    SCIENCE 


145 


Boric  Acid,  81 

Botticher,  78 

Bouchardat,  64 

Boullay,  86 

Boyle,  35,  90,  123 

Braconnot,  45 

Bradbury,  130 

Brandy,  113 

Brewing,  104 

Erin's  Process,  128       . 

Brown,  A.  J.,  107 

Brunner,  15 

Brunner,  Mond  and  Co.,  32 

Buchner,  107 

Bunsen,  15 

Butadiene,  64 

Butter  Substitutes,  58 


CALLENDAR,  79 
Calomel,  83 
Calotype  Process,  91 
Camphor,  55 
Candles,  57 
Caoutchouc,  63 
Carbohydrates,  48 
Carbolic  Acid,  39 
Carbon  Bisulphide,  84 
Carbonic  Acid  Gas,  103,  108 
Carbon  Printing  Process,  93 

Tetrachloride,  85 

Carbonyl  Chloride,  131 
Carborundum,  69 
Castner,  15,  32 
Catalyst,  Poisoning  of,  26 
Catalytic  Agents,  31 
Cattermole,  8 
Caustic  Potash,  81 

Soda,  28,  81 

Cavendish,  125,  126 
Caventou,  88 
Cellon,  52 
Celluloid,  52 
Cellulose,  48 
Cement,  65 
Cementation,  2,  3 


Chamois  Leather,  61 
Chance-Claus  Method,  29 
de  Chardonnet,  51 
Chevreul,  56 
Chloral,  86 
Chlorates,  33 
Chlorate  of  Potash,  30, 
Chlorine,  131 

,  Recovery  of,  30,  32 

Chloroform,  85 
Chrome-tan,  61 
Chromium,  17 

Cinnamoylsalicylic        Anhy- 
dride, 89 
Citric  Acid,  80 
Clark  (Water  Treatment),  6 
Claudet,  29 
Claus,  29 
Clayton,  35 
Cleaning  Spirit,  54 
Coal,  34 
Coal-gas,  35 
Coal  Tar,  36 
Cocaine,  89 
Cochineal,  41 
Coke,  34 

Cold  Storage,  103 
Colloidal  State,  61 
Colour  Photography,  93 
Contact  Agents,  31 

Process,  26 

Conte,  120 
Cookworthy,  65,  78 
Copper,  10 

in  Pyrites,  29 

,  Salts,  84 

Cordite,  46 

Corrosive  Sublimate,  83 
Cowles,  130,  131 
Cresylic  Acid,  39 
Cronstedt,  14 
Crookes,  97 
Cross  and  Be  van,  52 
Cyanamide  Process,  97 
Cyanamides,  83 
Cyanides,  62,  83,  97 
Cymogene,  54,  103 


146 


WHAT    INDUSTRY   OWES 


DAGUERRE,  90 

Dale,  48 

D'Arcet,  20 

Davy,  Edmund,  130 

Davy,  H.,  15,  16,  25,  81,  90, 

131 

Deacon,  31 
Debray,  20 
Delprat,  8 
Descotils,  20 
Desmond,  61 
Deville,  15,  17,  20 
Dewar,  130 
Diastase,  106 

Diffusion  Process,  101,  102 
Disinfectants,  89 
Dobereiner,  71 
Dowson  Gas,  35 
Drugs,  88 
Dry  Plates,  92 
Dye  Industry,  41 
Dyeing,  44 

Dyer  and  Hemming,  32 
Dyes,  Artificial ;  Advantages 

of,  42 
Dynamite,  47 


EGGS,  Preservation  of,  83 
Ehrlich,  89 
Eitner,  62 
Elmore,  7,  8 
Elution,  Process,  102 
Enamels,  75 
Epsom  Salts,  83 
Esparto,  50 
Essential  Oils,  55 
Ether,  86 

,  Extraction  by,  12 

Everson,  7 
Explosives,  44 

FATS,  53 

Feeding-stuffs,  98 
Fermentation,  107 
Ferrochrome,  17 
Ferromanganese,  3 


Ferro  vanadium,  19 

Fertilisers,  95 

Fertilisers  and  Feeding  Stuffs 

Act,  98 
F&y,  79 

Filaments,  Electric  Lamp,  17 
Fine  Chemicals,  86 
Fire-extinguisher,  85 
Fleurscheim,  47 
Flotation  of  Minerals,  7 
Food,  95,  99 
Formic  Acid,  80 
Fox  Talbot,  91 
Fraunhofer,  71 
Freezing  Agents,  103 
Fuel,  Economy  of,  6 
Fusel  Oil,  114 


CANISTER,  69 
Gas  Carbon,  37,  69 

,  Illuminating,  34,  54 

Gas  Light  and  Coke  Co.,  36 
Gasolene,  54 
Gay-Lussae,  25,  48 
Gelatine  Dynamite,  47 
Glass,  70 

,  Etching  of,  81 

,  Optical,  71 

,  Resistant,  72 

for  Thermometers,  72 

Gin,  114 
Glover,  25 
Glucose,  106 
Glue,  62 
Glycerine,  56 
Gold,  19 

in  Pyrites,  29 

Salts,  84 

Goodyear,  63 

Gossage,  30 

Government  Chemistry,  133 

Graham,  102 

Graphite,  69,  119,  120 

Ores,  7 

Guinand,  71 
Guncotton,  45 


TO    CHEMICAL    SCIENCE 


147 


Gunpowder,  45 
Guthrie,  85 


HABER'S  Process,  126 
Hadfield,  5 
Hales,  124 
Hampson,  129 
Hancock,  63 
Harcourt,  71 
Harden,  107 
Hardening  of  Oils,  14 
Hare,  20,  130 
Harries,  64 
Heinzerling,  62 
Hemming,  32 
Henderson,  29 
Herschel,  91 
Heumann,  43 
Hides,  Treatment  of,  60 
Hops,  106 
Huntsman,  2 
Hydrochloric  Acid,  30 
Hydroflouric  Acid,  81 
Hydrogen,  125 
Hydrogen  Peroxide,  83 
Hydrogenite,  128 
Hydrolith,  128 
Hyoscine,  88 
Hyoscyamine,  88 
Hypo,  83 
Hypochlorites,  33 


INDIGO,  42 

,  Artificial,  25 

Inks,  117 
Insecticides,  89 
Invert  Sugar,  106 
Iridium,  20 
Iron  Sulphate,  84 
Isoprene,  63 


JACKSON,  C.,  86 
Janetty/20  ' 


Jaubert,  128 

Johnson,  Matthey  and  Co.,  20 


KAINITE,  82 
Kekule,  130 
Kerosene,  54 
Kestner,  24 
Knapp,  62 
Knight,  20 


LACTIC  Acid,  80,  113 
Lamp  Oil,  54 
Lampadius,  84 
Laughing  Gas,  83,  131 
Laurent,  47 
Lavoisier,  125 
Lawrence,  85 
Lead  Azide,  84 

Carbonate,  84 

Chamber  Process,  24 

,  Desilverisation  of.  11 

,  Purity  of,  13 

Leather,  59 

Leather  Cloth,  62 

Leblanc,  27 

Le  Bon,  36 

Le  Chatelier,  4,  65,  79 

Lefevre,  24 

Lemery,  24,  126 

Liebig,  107 

Lignocellulose,  50 

Ligroin,  54 

Linde,  129 

Linde-Frank-Caro      Process, 

128 

Lipmann,  93 
Liqueurs,  114 
Liquid  Air  Process,  129 
Lumiere,  93 
Lupulin,  106 
Lyddite,  47 


MAC  ARTHUR-FORREST,  19 
Macintosh,  63 


148 


WHAT    INDUSTRY   OWES 


Madder,  42 
Magnalium,  16 
Magnesia,  82 
Magnesium,  16 

Sulphate,  83 

Magnetic  Separation,  10 

Malt,  105 

Mantles,  Gas,  18 

Marggraf,  101 

Marriotte,  123 

Martens,  4 

Matthews,  64 

Mauveine,  44 

Mayow,  124 

McDougall  and  Howies,  97 

Melinite,  47 

Mercury  Fulminate,  83 

Messerschmitt  Process,  127 

Metallography,  4 

Methyl  Alcohol,  110 

Methyl  Chloride,  103 

Mineral  Tannages,  61 

Minerals,  Separation  of,  7 

Moissan,  17,  130 

Molybdenum,  16 

Monazite,  18 

Mond.  14,  32 

Gas,  35 

Mordants,  44 
Mortar,  65 
Motor  Spirit,  54 
Murdock,  35 
31uspratt,  27 


NEOSALVARSAN,  89 
Nickel,  14 
Nicotine,  116,  117 
Niepce,  90 
Nitrides,  97 
Nitrogen,  131 
,  Fixation  of,  96 

Nitroglycerine,  46 

Nobel,  46 

Nordhausen,  26 

Novocaine,  89 


OILS,  Animal,  55 

,  Hardening  of,  14 

,  Vegetable,  55 

Osmium,  20 
Osmond,  4 
Osmose  Process,  102 
Ostwald,  127 
Oxalic  Acid,  48,  80 
Oxygen,  128 
Ozone,  129 


PALLADIUM,  21 

Paper,  49 

Paracelsus,  126 

Paraffin  Wax,  54 

Parker,  66 

Parkes,  11,  12,  13 

Parting  of  Gold,  20 

Pasteur,  107 

Pattinson,  11 

Pelletier,  88 

Pencils,  119 

Percarbonates,  83 

Perfumes,  56 

Perkin,  44,  64 

Peroxy  Compounds,  83 

Persulphates,  83 

Petrol,  54 

Petroleum,  Distillation  of,  54 

Phenacetin,  89 

Phosgene,  131 

Photographic  Materials,  94 

Photography,  90 

Piat,  63 

Picric  Acid,  47 

Pitch,  36 

Platinum,  20 

Salts,  84 

Plattner,  19 

Plenist  Controversy,  123 
Plumbago,  119 
Poison  Gases,  131 
Porcelain,  77 
Potassium  Salts,  81 

Thiocarbonate,  85 

Pott,  78 


TO    CHEMICAL    SCIENCE 


149 


Potter,  8 

Potter's  Cones,  78 
Pottery,  77 
Priestley,  63,  125,  131 
Procter,  59,  62 
Puering,  60 
Pulvis  Fulminans,  45 
Pyrometer,  79 

QUININE,  88 


RAMSAY,  125 
Rayleigh,  125 
Refractory  Materials,  68 
Reid,  46 
Rhigolene,  54 
Rhodium,  21 
Roberts -Austin,  4 
Roebuck,  24 
Rolland,  32 
Rubber,  63 

,  Synthetic,  64 

Rum,  114 
Rutherford,  124 


SABATIEB,  127 

Salicylic  Acid,  81,  88 

Salipyrene,  89 

Salts,  82 

Salvarsan,  89 

Sauveur,  4 

Scheele,  20,  90,  125,  131 

Scheibler,  102 

Schloessing,  32 

Schonbein,  45 

Schott,  71 

Schultz,  62 

Sefstrom,  19 

Seguin,  61 

Senderens,  127 

Separation,  Magnetic,  10 

Sepia,  41 

Shale  Oil,  55 

Shimose,  47 

Sicoid,  52 


Siemens,  4,  129,  130 

and  Halske,  20 

Silica,  Fused,  69,  73 
Silicon,  69 

Silk,  Artificial,  48,  5 1 
Silver  in  Pyrites,  29 

Salts,  84 

Simmonds,  79 
Simpson,  85 
Smeaton,  65 
Smelling  Salts,  83 
Soap,  56 
Sobrero,.46 
Soda  Ash,  28 
Sodium,  15 

—  Bicarbonate,  28,  31 

Carbonate,  28 

Salts,  83 

Peroxide,  83 

Solar  Oils,  55 

Solvay,  28,  31,  32 

Solvents,  84 

Sorby,  4 

Soret,  129 

Souberain,  85 

Spiegel,  3 

Spirits,  112 

Stead,  4 

Steel,  2 

Steels,  Microscopic  Structure 

of,  4 

,  Special,  5 

Steffen,  102 

Stolzel,  78 

Stoveine,  89 

Strange,  64 

Strontium  Hydroxide,  82 

Salts,  83 

Strychnine,  88 

Suchsland,  117 

Sugar,  Beet,  101 

Sugar,  Cane,  100 

Sulphide  Ores,  Concentration 

of,  7 
Sulphur,  Recovery  of,  from 

Alkali  Waste,  29 

— ,  Chloride,  84 

L  2 


150 


WHAT    INDUSTRY    OWES 


Sulphuric  Acid,  22 

,  Fuming,  26 

,  Impurities  in,  87 

,        Removal        of 

Arsenic  from,  27 
Superphosphate  of  Lime,  96 
Swan,  62 
Swartz,  45 


TALBOTYPE  Process,  91 
Tar,  Distillation  of,  36 

Fractions,  38 

Tartaric  Acid,  80 

Tavener,  20 

Tawing,  61 

Tennant,  20 

Tetranitroaniline,  47 

Thermite  Process,  17,  19 

Thomas  and  Gilchrist,  3 

Thorium,  17 

Thorpe,  79 

Tilden,  64 

Tin  Ore,  Concentration  of, 

Salts,  84 

T.N.T.,  45 
Tobacco,  115 
Toluene,  39 
Tolypyrene,  89 
Trimethylamine,  81,  103 
Trinitrotoluene,  45 
Tungsten,  16 
Tyrian  Purple,  41 


UNVERDORBEN,  44 


VALENTINE,  23 
Van  Helmont,  122 
VanMarum,  129 
Vanadium,  19 
Vaseline,  54 


Vauquelin,  17 
Vegetable  Tanning,  61 
Vergara,  96 
Veronal,  89 
Vieille,  46 
Vohl,  130 
Vulcanising,  63 


WASHING  Soda,  28 
Water,  for  Brewing,  1 05 

Gas,  34 

Glass,  83 

,  Softening  of,  6 

Watson,  35 

Watt,  119 

Waxes,  53,  57 

Wedgwood,  90 

Weldon,  31 

Weldon  Process,  131 

Welsbach,  19 

Welter,  47 

West-Knight  and  Gall,  39 

Whiskey,  113 

Williams,  63 

Willson,  131 

Wines,  111 

Winsor,  36 

Wohler,  15,  17,  130 

Wollaston,  20 

Wood,  9 

,  Mechanical,  50 

Pulp,  51 

,  Chemical,  50 

Spirit,  110 

Wort,  105 


YOUNG,  55 


ZINC  Chloride,  83 
Zirconia,  69 


Printed  by  GEORGB  RKVEIBS,  LD.,  Greystoke  Place,  Fetter  Lane,  E.G. 


STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURM 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
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OVERDUE. 


warm 

MAY  17  1937 

" 

25Apr'58BB 

PEC'O  ID 

APR  1  1  1958 

LD  2  1-1  00m-  8 

/ 


/ 


YB   15476 


387485 

-T~ 
UNIVERSITY  OF  CALIFORNIA  LIBRARY 


